v3.3.1.900
INCOME TAXES - Effective income tax rate on earnings (Details) - USD ($)
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
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 $ 57,237,000 $ 34,035,000 $ 34,902,000
Effect of:      
State income taxes 6,180,000 195,000 1,479,000
Increase (decrease) in reserve for uncertain tax positions (1,031,000) 1,050,000 2,193,000
Federal and state credits (2,686,000) (2,985,000) (2,600,000)
Change in net operating loss carryforward for excess tax deductions     (28,206,000)
Permanent items 101,000 1,485,000 537,000
Other items 155,000 (1,100,000) (6,088,000)
Valuation allowance (281,000) 790,000 (265,600,000)
Income Tax Expense (Benefit) $ 59,675,000 $ 33,470,000 $ (263,383,000)
Effective income tax rate (as a percent) 36.50% 34.40% (264.10%)
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 (2,200,000)   $ (500,000)
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