Commercial Paper (Details) - USD ($)	3 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Oct. 31, 2014
Short-term Debt [Line Items]
Outstanding borrowings	$ 300,000,000	$ 0
Commercial Paper
Short-term Debt [Line Items]
Maximum borrowing capacity			$ 1,000,000,000
Maximum amount outstanding during period	300,000,000
Outstanding borrowings	$ 300,000,000	$ 0