Long-Term Debt and Short-Term Borrowings (Details) $ in Millions	1 Months Ended	3 Months Ended
	Aug. 31, 2014 USD ($)	Mar. 31, 2016 USD ($)
Line of Credit Facility
Required minimum EBITDA to Interest Ratio		3.0
Actual EBITDA to Interest Ratio		51
Number of consecutive quarters over which the ratio of required EBITDA to Interest Ratio is calculated		4
Five-year credit facility agreement
Line of Credit Facility
Term of credit facility	5 years	5 years
Credit facility amount prior to new agreement	$ 2,250
Current borrowing capacity		$ 3,750
Maximum increase available subject to lender approval		1,250
Maximum borrowing capacity including portion subject to lender approval		$ 5,000