Equity (Detail) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 01, 2015
Stock Repurchase [Line Items]
Repurchase of common stock	$ 5,389,000	$ 4,997,000	$ 25,036,000
Common Stock [Member]
Stock Repurchase [Line Items]
Stock repurchase program, authorized amount (in shares)				$ 25,000,000.0
Repurchase of common stock (in shares)	0.4
Repurchase of common stock	$ 5,400,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 14,600,000