Represents the number of grants that will be made on achieving specified percentage of performance target.

No definition available.

Name:	amch_AwardsToBeGrantedOnAchievingSpecifiedPercentageOfPerformanceTarget
Namespace Prefix:	amch_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount of debt identified as being convertible into another form of financial instrument (typically the entity's common stock) as of the balance sheet date, which originally required full repayment more than twelve months after issuance or greater than the normal operating cycle of the company.

+ References

No definition available.

STOCKHOLDERS' EQUITY (Details)								1 Months Ended		3 Months Ended						9 Months Ended
STOCKHOLDERS' EQUITY (Details)	Nov. 01, 2018 USD ($)	Sep. 30, 2018 USD ($) item $ / shares shares	Sep. 14, 2018 USD ($) item $ / shares shares	Jul. 24, 2018 USD ($) $ / shares	May 03, 2018 USD ($) $ / shares	Feb. 28, 2018 USD ($) $ / shares	Mar. 31, 2017 USD ($) item $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Mar. 31, 2018 $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) shares	Mar. 31, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) shares	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) $ / shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Dividends
Cash dividend declared (in dollars per share) \| $ / shares			$ 1.55	$ 0.20	$ 0.20	$ 0.20
Dividends declared			$ 162,900,000	$ 25,800,000	$ 26,000,000	$ 26,000,000
Dividends and dividend equivalents																$ 237,400,000	$ 78,700,000
Shares surrendered to pay for payroll taxes, value												$ 1,800,000			$ 6,500,000
Additional Public Offering
Value of shares issued														$ (900,000)	617,700,000		616,800,000
Net proceeds																	616,800,000
Additional paid-in capital		$ 1,994,500,000						$ 1,994,500,000		$ 1,994,500,000						1,994,500,000		$ 2,241,600,000
Price per share (in dollars per share) \| $ / shares									$ 5.19			$ 5.19
Value of stock repurchased and canceled										422,900,000						422,900,000
Reclassification from temporary equity											$ 100,000	$ 300,000		300,000
Treasury Stock
Cost of treasury shares											$ 8,200,000		$ 16,500,000
Equity disclosures
Price per share (in dollars per share) \| $ / shares									$ 5.19			$ 5.19
Treasury Stock
Treasury Stock
Number of treasury shares purchased \| shares											500,000		1,068,300
Cost of treasury shares											$ 8,200,000		$ 16,500,000
Additional Paid-in Capital
Dividends
Shares surrendered to pay for payroll taxes, value												$ 1,800,000			6,500,000
Additional Public Offering
Value of shares issued														(900,000)	$ 617,500,000
Value of stock repurchased and canceled										256,700,000
Reclassification from temporary equity											$ 100,000	$ 300,000		$ 300,000
G&A: Other
Equity disclosures
Stock-based compensation expense included in general and administrative expenses										4,200,000			$ (100,000)			10,900,000	$ 3,900,000
Senior Unsecured Convertible Notes due 2024
Additional Public Offering
Carrying value		$ 642,300,000	$ 587,500,000					$ 642,300,000		$ 642,300,000						$ 642,300,000
Price per share (in dollars per share) \| $ / shares		$ 20.50						$ 20.50		$ 20.50						$ 20.50
Number of shares upon conversion										5,900,000						2,000,000
Equity disclosures
Price per share (in dollars per share) \| $ / shares		$ 20.50						$ 20.50		$ 20.50						$ 20.50
Maximum
Additional Public Offering
Ownership percentage		50.00%						50.00%		50.00%						50.00%
RSU and PSU Units
Equity disclosures
Restricted stock unit granted (in shares) \| shares																1,313,152
Shares of RSU and PSU
Balance at the beginning of the period (in shares) \| shares												1,083,841				1,083,841
Granted (in shares) \| shares																1,313,152
Vested (in shares) \| shares																(195,432)
Forfeited (in shares) \| shares																(27,870)
Nonvested at the end of the period (in shares) \| shares		2,173,691						2,173,691		2,173,691						2,173,691
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share) \| $ / shares												$ 28.61				$ 28.61
Granted (in dollars per share) \| $ / shares																15.65
Vested (in dollars per share) \| $ / shares																28.46
Forfeited (in dollars per share) \| $ / shares																20.49
Unvested at the end of the period (in dollars per share) \| $ / shares		$ 20.90						$ 20.90		$ 20.90						$ 20.90
Members of management and executive officers \| Performance Vesting
Equity disclosures
Restricted stock unit granted (in shares) \| shares									653,669
Number of days from the termination of service for settlement of fully vested units																30 days
Period of cumulative adjusted EBITDA, diluted earnings pershare, and net profit results to meet the performance target condition																3 years
Awards to be granted upon achieving 100% of performance target (in shares) \| shares							653,669
Shares of RSU and PSU
Granted (in shares) \| shares									653,669
Members of management and executive officers \| Performance Vesting \| Minimum
Equity disclosures
PSUs vesting as a percentage of performance target																80.00%
Percentage of performance target																30.00%
Members of management and executive officers \| Performance Vesting \| Maximum
Equity disclosures
PSUs vesting as a percentage of performance target																120.00%
Percentage of performance target																200.00%
Members of management and executive officers \| Performance Vesting \| Prior to January 2, 2019
Equity disclosures
Awards forfeited (as a percent)		66.67%						66.67%		66.67%						66.67%
Members of management and executive officers \| Performance Vesting \| Prior to January 2, 2020
Equity disclosures
Awards forfeited (as a percent)		33.33%						33.33%		33.33%						33.33%
Employee
Equity disclosures
Increase (decrease) to additional paid-in capital related to stock based compensation																$ 400,000
Shares of RSU and PSU
Forfeited (in shares) \| shares																(37,105)
2013 Equity Incentive Plan \| RSU and PSU Units
Equity disclosures
Fair value of stock at grant date (in dollars per share) \| $ / shares							$ 15.65
2013 Equity Incentive Plan \| Members of management \| Restricted stock unit
Equity disclosures
Restricted stock unit granted (in shares) \| shares							653,669
Number of shares to be received for each unit \| shares		1						1		1						1
Number of days from the termination of service for settlement of fully vested units																30 days
Grant date fair value (in dollars)							$ 10,200,000
Shares of RSU and PSU
Granted (in shares) \| shares							653,669
Related Party Transactions
Percentage of options that will vest on each of the anniversaries from the date of grant																33.00%
2013 Equity Incentive Plan \| Members of management \| Performance Vesting
Additional Public Offering
Price per share (in dollars per share) \| $ / shares							$ 15.65								$ 15.65
Equity disclosures
Price per share (in dollars per share) \| $ / shares							$ 15.65								$ 15.65
2013 Equity Incentive Plan \| Executive officers \| Restricted stock unit
Related Party Transactions
Vesting period (in years)																3 years
Class A common stock \| Subsequent Events
Dividends
Dividends declared	$ 0.20
Class A common stock \| Senior Unsecured Convertible Notes due 2024
Additional Public Offering
Number of shares upon conversion		31,662,269														31,662,269
Class A common stock \| 2013 Equity Incentive Plan \| Board of Director
Equity disclosures
Number of Board of Directors to whom common stock was granted \| item							5
Shares granted \| shares							28,055
Class A common stock \| 2013 Equity Incentive Plan \| Board of Director \| Other General And Administrative Expense Caption [Member]
Equity disclosures
Stock-based compensation expense included in general and administrative expenses																$ 500,000
Class B common stock \| Subsequent Events
Dividends
Dividends declared	$ 0.20
Class B common stock \| Senior Unsecured Convertible Notes due 2024
Additional Public Offering
Common stock repurchased and cancellation (in shares) \| shares			24,057,143
Price per share (in dollars per share) \| $ / shares			$ 17.50
Value of stock repurchased and canceled			$ 421,000,000
Number of shares upon conversion \| item			5,666,000
Equity disclosures
Price per share (in dollars per share) \| $ / shares			$ 17.50
Wanda
Additional Public Offering
Receivable due from related party		$ 800,000						$ 800,000		$ 800,000						800,000		600,000
Reimbursements																$ 700,000
Ownership percentage		50.01%						50.01%		50.01%						50.01%
Combined voting power held in Holdings (as a percent)		75.01%						75.01%		75.01%						75.01%
Related Party Transactions
Receivable due from related party		$ 800,000						$ 800,000		$ 800,000						$ 800,000		$ 600,000
Wanda \| Minimum
Additional Public Offering
Ownership percentage			50.10%
Wanda \| Class A common stock
Additional Public Offering
Voting ratio between Class B and Class A common stock								three-to-one voting ratio
Wanda \| Class B common stock
Additional Public Offering
Shares owned \| shares		51,769,784						51,769,784		51,769,784						51,769,784
Number of shares upon conversion								5,666,000