Condensed Consolidating Financial Statements (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 2,895,000	$ 2,706,000
Parent Percentage of Ownership in Guarantor Subsidiaries	100.00%
7.75% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.75%	7.75%
4.75% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.75%	4.75%
5.00% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.00%
Senior Notes [Member] | 7.75% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 0	$ 700,000
Senior Notes [Member] | 4.75% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	600,000	600,000
Senior Notes [Member] | 5.00% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 1,000,000	$ 0