Share Repurchase Programs (Detail) - USD ($)	5 Months Ended	6 Months Ended	41 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Aug. 31, 2017	Aug. 31, 2014
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 50,000,000
Purchase of common stock, shares			1,316,587,000
Purchase of Treasury Stock		$ 49,875,000	$ 19,000,000
Offering and Sale of Notes
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program, authorized amount				$ 50,000,000
Purchase of common stock, shares	1,414,900,000
Purchase of Treasury Stock	$ 49,900,000
Program
Equity Class Of Treasury Stock [Line Items]
Purchase of common stock, shares		0