v3.7.0.1
INCOME TAXES - Effective income tax rate on earnings (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Reconciliation of effective tax rate on earnings (loss) from continuing operations before income taxes and the U.S. federal income tax statutory rate      
Income tax expense at the federal statutory rate $ 52,374,000 $ 57,237,000 $ 34,035,000
Effect of:      
State income taxes 6,460,000 6,180,000 195,000
Increase (decrease) in reserve for uncertain tax positions (19,152,000) (1,031,000) 1,050,000
Federal and state credits (2,690,000) (2,686,000) (2,985,000)
Permanent items - transaction costs 5,655,000 101,000 1,485,000
Permanent items - other 4,378,000    
Foreign rate differential (2,222,000)    
Change in legislation (9,856,000)    
Other items 265,000 155,000 (1,100,000)
Valuation allowance $ 2,760,000 $ (281,000) $ 790,000
Effective income tax rate (as a percent) 25.40% 36.50% 34.40%
Reduction of uncertain tax positions and net discrete tax benefit   $ 2,900,000  
Net discrete benefit for reduction of uncertain tax positions   2,100,000  
Gross decreases-tax position in prior periods   800,000  
Increase of uncertain tax positions and net discrete tax provision $ 19,200,000 2,200,000  
Net discrete tax provision for interest   1,000,000  
Net discrete tax provision for interest, net of tax   (610,000)  
Deferred tax assets reinstated   9,200,000  
Interest and taxes payable   $ 10,200,000