Stockholders' Equity - Treasury Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Total Number of Shares Purchased
Total number of shares purchased, beginning balance (shares)
Shares purchased during period (shares)	572,550
Total number of shares purchased,ending balance (shares)	572,550
Average price paid per share, beginning balance (usd per share)
Average price paid per share (usd per share)	17.47
Average price paid per share, ending balance (usd per share)	$ 17.47
Approximate dollar value of shares that may yet be purchased under the publicly announced plans or programs		$ 10,000
Common Stock Repurchase Program
Total Number of Shares Purchased
Total number of shares purchased, beginning balance (shares)
Shares purchased during period (shares)	572,550
Total number of shares purchased,ending balance (shares)	572,550