Long-Term Debt and Other Borrowing Arrangements - Carrying Values of Long-Term Debt and Other Borrowing Arrangements (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total senior subordinated notes	$ 1,526,980,000	$ 1,584,232,000
Less unamortized debt issuance costs	(23,383,000)	(23,484,000)
Long-term debt	1,503,597,000	1,560,748,000
Revolving credit agreement due 2022
Debt Instrument [Line Items]
Revolving credit agreement due 2022	0	0
3.875% Senior subordinated notes due 2028
Debt Instrument [Line Items]
Total senior subordinated notes	$ 411,110,000	$ 0
Senior subordinated notes interest rate	3.875%	3.875%
3.375% Senior subordinated notes due 2027
Debt Instrument [Line Items]
Total senior subordinated notes	$ 528,570,000	$ 540,810,000
Senior subordinated notes interest rate	3.375%	3.375%
4.125% Senior subordinated notes due 2026
Debt Instrument [Line Items]
Total senior subordinated notes	$ 234,920,000	$ 240,360,000
Senior subordinated notes interest rate	4.125%	4.125%
2.875% Senior subordinated notes due 2025
Debt Instrument [Line Items]
Total senior subordinated notes	$ 352,380,000	$ 360,540,000
Senior subordinated notes interest rate	2.875%	2.875%
5.25% Senior subordinated notes due 2024
Debt Instrument [Line Items]
Total senior subordinated notes	$ 0	$ 200,000,000
Senior subordinated notes interest rate	5.25%	5.25%
5.50% Senior subordinated notes due 2023
Debt Instrument [Line Items]
Total senior subordinated notes	$ 0	$ 242,522,000
Senior subordinated notes interest rate	5.50%	5.50%