Long-term Debt - Summary of Long-term Debt (Details) - Senior Notes [Member] - USD ($) |
1 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|
Feb. 28, 2015 |
Jun. 30, 2015 |
Dec. 31, 2014 |
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| Debt Instrument [Line Items] | |||||||||
| Net proceeds | $ 1,482,400,000 | ||||||||
| Debt issuance costs, net | $ 17,600,000 | ||||||||
| 5.375% Senior Notes [Member] | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Principal Amount at Par | $ 500,000,000 | $ 500,000,000 | |||||||
| Fair Value | [1] | $ 518,800,000 | $ 520,000,000 | ||||||
| Interest rate | 5.375% | 5.375% | |||||||
| 5.750% Senior Notes [Member] | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Principal Amount at Par | $ 400,000,000 | $ 400,000,000 | |||||||
| Fair Value | [1] | $ 411,000,000 | $ 416,000,000 | ||||||
| Interest rate | 5.75% | 5.75% | |||||||
| 5.50% Senior Notes [Member] | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Principal Amount at Par | [2] | $ 700,000,000 | |||||||
| Fair Value | [1],[2] | $ 722,800,000 | $ 0 | ||||||
| Interest rate | 5.50% | 5.50% | [2] | ||||||
| 5.875% Senior Notes [Member] | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Principal Amount at Par | [2] | $ 800,000,000 | |||||||
| Fair Value | [1],[2] | $ 828,100,000 | $ 0 | ||||||
| Interest rate | 5.875% | 5.875% | [2] | ||||||
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