Long-Term Debt - 5% Senior Notes (Details) - USD ($)				3 Months Ended		12 Months Ended
	Aug. 01, 2019	Apr. 16, 2018	Apr. 03, 2017	Sep. 30, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 23, 2012
Debt, Long-term and Short-term, Combined Amount						$ 2,258,873,000	$ 2,317,723,000
Gain (Loss) on Extinguishment of Debt				$ (1,700,000)	$ (2,500,000)	$ (1,676,000)	(2,493,000)	$ (7,052,000)
Senior Notes [Member] | Five Percent Senior Notes due 2020 [Member]
Debt Instrument, Redemption Price, Percentage Plus Accrued and Unpaid Interest		100.00%	101.25%
Early Repayment of Senior Debt		$ 280,000,000.0	$ 220,000,000.0
Gain (Loss) on Extinguishment of Debt							$ (1,400,000)	$ (4,400,000)
Senior Notes [Member] | Five and One Half Percent Senior Notes due 2022 [Member]
Debt Instrument, Redemption Price, Percentage Plus Accrued and Unpaid Interest	100.00%
Early Repayment of Senior Debt	$ 300,000,000
Five Percent Senior Notes due 2020 [Member]
Debt, Long-term and Short-term, Combined Amount									$ 500,000,000