Debt (Details) (USD $)	0 Months Ended		3 Months Ended	1 Months Ended
	Mar. 27, 2015	Feb. 06, 2015	Mar. 31, 2015	Jan. 31, 2015	Dec. 31, 2014
Long-term debt
Long-term Debt			$ 3,825,456,000		$ 4,355,049,000
Other			8,739,000		6,209,000
Less: Current portion			8,739,000		6,190,000
Long-term debt			3,816,717,000		4,348,859,000
Unsecured term loan facility		300,000,000
Unsecured debt maturity period		3 years
Prepayment of loan upon closing the merger			70,000,000
Payment of debt principal	300,000,000		300,000,000
2.35% senior notes due September 2016
Long-term debt
Senior Notes			349,904,000		349,887,000
Interest rate on senior notes due (as a percent)			2.35%
6.15% senior notes due February 2018
Long-term debt
Senior Notes			931,000,000		930,693,000
Interest rate on senior notes due (as a percent)			6.15%
9.25% senior notes due January 2019
Long-term debt
Senior Notes			339,607,000		339,607,000
Interest rate on senior notes due (as a percent)			9.25%
5.00% senior notes due September 2020
Long-term debt
Senior Notes			698,329,000		698,253,000
Interest rate on senior notes due (as a percent)			5.00%
4.625% senior notes due September 2021
Long-term debt
Senior Notes			698,448,000		698,388,000
Interest rate on senior notes due (as a percent)			4.625%
5.10% senior notes due September 2023
Long-term debt
Senior Notes			348,925,000		348,893,000
Interest rate on senior notes due (as a percent)			5.10%
Commercial paper
Long-term debt
Long-term Debt			250,504,000		533,119,000
Aggregate amount of senior notes			250,500,000
Weighted average interest rate on revolving credit facilities (as a percent)			0.664%
Commercial paper | Minimum
Long-term debt
Remaining period to maturity			1 year
Revolving Credit Facility
Long-term debt
Revolving credit facility			200,000,000		450,000,000
Weighted average interest rate on revolving credit facilities (as a percent)			1.47%
Increase in borrowing capacity				225,000,000
Maximum borrowing capacity				$ 1,725,000,000