Debt Credit Facility (Details) - Revolving Credit Facility [Member] $ in Millions	3 Months Ended
	Sep. 30, 2017 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,800
Line of Credit Facility, Former Borrowing Capacity	2,000
Line of Credit Facility, Accordion Feature	750
Line of Credit Facility, Fair Value of Amount Outstanding	0
Letters of Credit Outstanding, Amount	$ 0
Line of Credit Facility, Annual Fee Percentage	0.20%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate, Base Rate	0.70%
Line of Credit Facility, Interest Rate, LIBOR Plus All-in Spread Rate	1.70%
All-in Interest Rate Spread Based on Credit Rating	1.175%
Line of Credit Facility, Annual Fee Percentage	0.30%
Line of Credit Facility, Covenant Terms	4.25x
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate, Base Rate	0.00%
Line of Credit Facility, Interest Rate, LIBOR Plus All-in Spread Rate	1.00%
All-in Interest Rate Spread Based on Credit Rating	0.175%
Line of Credit Facility, Annual Fee Percentage	0.125%
Line of Credit Facility, Covenant Terms	3.00x
Previous Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Date	Mar. 31, 2019
Letter of credit, credit facility sub-facility, maximum borrowing amount	$ 300
Debt Issuance Costs, Gross	$ 2
Amended and Restated Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Date	Aug. 31, 2022
Letter of credit, credit facility sub-facility, maximum borrowing amount	$ 250
Debt Issuance Costs, Gross	$ 5