Condensed Consolidating Financial Statements (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 3,141,625	$ 3,152,584
Parent percentage of ownership in guarantor subsidiaries	100.00%
4.75% Notes due December 2022
Debt Instrument [Line Items]
Interest rate	4.75%
5.00% Notes due April 2024
Debt Instrument [Line Items]
Interest rate	5.00%
4.75% Notes due August 2025
Debt Instrument [Line Items]
Interest rate	4.75%
Senior Notes | 4.75% Notes due December 2022
Debt Instrument [Line Items]
Long-term debt	$ 600,000	600,000
Senior Notes | 5.00% Notes due April 2024
Debt Instrument [Line Items]
Long-term debt	1,000,000	1,000,000
Senior Notes | 4.75% Notes due August 2025
Debt Instrument [Line Items]
Long-term debt	$ 800,000	$ 800,000