Debt (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Debt [Line Items]    
Revolving credit agreement $ 19,602,000 $ 0
Original issue premium 6,722,000 7,017,000
Debt, Long-term and Short-term, Combined Amount, Total 761,324,000 742,017,000
Obligations under capital leases 1,007,000 1,110,000
Debt and Capital Lease Obligations 762,331,000 743,127,000
Less current portion: 532,000 534,000
Long-term Debt, Excluding Current Maturities, Total 761,799,000 742,593,000
Notes due 2020    
Debt [Line Items]    
Senior Notes $ 735,000,000 $ 735,000,000