XML 53 R39.htm IDEA: XBRL DOCUMENT v3.19.1
Debt (Details) - USD ($)
Mar. 31, 2019
Dec. 31, 2018
Debt [Line Items]    
Revolving credit agreement $ 32,803,000 $ 68,143,000
Debt issuance costs (13,753,000) (14,036,000)
Debt, Long-term and Short-term, Combined Amount, Total 919,050,000 954,107,000
6.50% Notes due 2024    
Debt [Line Items]    
Senior Notes $ 900,000,000 $ 900,000,000