Long-Term Debt Interest Rates (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Feb. 01, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	Jan. 12, 2015	Dec. 31, 2014	Jan. 20, 2005
Debt Instrument [Line Items]
Repayments of long-term debt			$ 1,331,648	$ 3,016
1.875% Senior Notes
Debt Instrument [Line Items]
Unamortized discount			$ 5,630			$ 6,605
Debt instrument, interest rate			1.875%			1.875%
3.00% Senior Notes
Debt Instrument [Line Items]
Unamortized discount			$ 275			$ 306
Debt instrument, interest rate			3.00%			3.00%
4.15% Senior Notes
Debt Instrument [Line Items]
Unamortized discount			$ 1,366			$ 1,439
Debt instrument, interest rate			4.15%			4.15%
4.50% Senior Notes
Debt Instrument [Line Items]
Unamortized discount			$ 1,714			$ 1,871
Debt instrument, interest rate			4.50%			4.50%
4.625% Senior Notes
Debt Instrument [Line Items]
Debt instrument, interest rate			4.625%		4.625%
Unamortized Premium			$ 40,203		$ 43,700
5.10% Senior Notes
Debt Instrument [Line Items]
Unamortized discount						$ 3
Debt instrument, interest rate						5.10%	5.10%
Repayments of long-term debt	$ 325,000
5.45% Senior Notes
Debt Instrument [Line Items]
Unamortized discount			$ 1,012			$ 1,029
Debt instrument, interest rate			5.45%			5.45%
Senior Unsecured Cash Bridge Facility | Bridge Loan
Debt Instrument [Line Items]
Repayments of long-term debt		$ 800,000
Short-term Debt | Term Loan
Debt Instrument [Line Items]
Repayments of long-term debt		1,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Repayments of long-term debt		$ 250,000