Bank Revolving Credit Facility (Details) - USD ($) $ in Billions	Jul. 20, 2016	Feb. 26, 2016
Subsequent Event [Line Items]
Debt instrument, term		397 days
Subsequent Event | Bank revolving credit facility due 2020
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 2.5
Line of credit facility, expiration date	Jul. 20, 2020
Debt instrument, term	4 years
Subsequent Event | Bank 364-day revolving credit facility due July 2017
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 1.0
Line of credit facility, expiration date	Jul. 19, 2017
Debt instrument, term	364 days