Debt (Revolving Credit Facility Under The Senior Credit Agreement) (Narrative) (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Feb. 05, 2015	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Repayments of revolving credit facility			$ 190,000	$ 895,000	$ 790,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			1,000,000
Line of credit facility, commitment fee	0.25%
Borrowings on the revolving credit facility			580,000
Repayments of revolving credit facility			190,000
Line of credit facility, outstanding			$ 390,000
Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Repayments of revolving credit facility		$ 95,000
Minimum [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.375%
Minimum [Member] | Revolving Credit Facility [Member] | Eurodollar [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.375%
Maximum [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.00%
Maximum [Member] | Revolving Credit Facility [Member] | Eurodollar [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	2.00%