Credit Facility - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 Five-year Unsecured Revolving Credit Facility [Member]	Oct. 31, 2013 Five-year Unsecured Revolving Credit Facility [Member]	Jun. 30, 2014 Five-year Unsecured Revolving Credit Facility [Member] Base Rate [Member]	Jun. 30, 2014 Five-year Unsecured Revolving Credit Facility [Member] Eurodollar [Member]	Oct. 31, 2013 Five-year Unsecured Revolving Credit Facility [Member] Maximum [Member]	Oct. 31, 2013 Five-year Unsecured Revolving Credit Facility [Member] Minimum [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility available amount			$ 650
Credit Agreement term			5 years
Letters of credit sublimit under credit facility			100
Maximum amount of credit facility			$ 900
Credit Agreement due date			Oct. 23, 2018
Interest on borrowings, description	Either (a) a Eurodollar Rate formula or (b) the Base Rate formula, each as set forth in the Credit Agreement
Operating income leverage ratio						3.00%
Interest coverage ratio							3.00%
Commitment fee percentage on undrawn balance		0.25%
Applicable margin for borrowing				0.50%	1.50%