Debt (Details) - USD ($)		1 Months Ended	6 Months Ended
		May 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Apr. 30, 2016
Financial Instruments
Amortization of debt issuance costs			$ 25,691,000	$ 2,166,000
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Financial Instruments
Notional amount of interest rate locks			3,600,000,000
Interest rate lock liability, pretax loss recognized in cumulative other comprehensive loss			174,700,000
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Financial Instruments
Interest rate lock liability	[1]		174,700,000
Line of Credit [Member] | Other Current Assets [Member]
Financial Instruments
Debt issuance costs			65,100,000
Line of Credit [Member] | Interest Expense [Member]
Financial Instruments
Amortization of debt issuance costs			24,400,000
Periodic fees			2,200,000
Bridge Loan [Member] | Line of Credit [Member] | Bridge Credit Agreement [Member]
Financial Instruments
Maximum borrowing capacity					$ 7,300,000,000
Borrowings outstanding			0
Publicly Traded Debt [Member]
Financial Instruments
Carrying Amount			1,906,672,000	1,114,952,000
Fair Value			2,021,174,000	1,129,742,000
Non-traded debt [Member]
Financial Instruments
Carrying Amount			4,724,000	4,894,000
Fair Value			4,451,000	$ 4,659,000
Line of Credit [Member] | Term Credit Agreement [Member]
Financial Instruments
Maximum borrowing capacity					$ 2,000,000,000
Borrowings outstanding			0
Line of Credit [Member] | May 2016, Five Year Credit Agreement [Member]
Financial Instruments
Maximum borrowing capacity		$ 150,000,000
Borrowings outstanding			$ 0
Term (in years)		5 years

[1] The interest rate lock liability is measured at the present value of the expected future cash flows using market-based observable inputs.