Schedule of Weighted Average Shares Outstanding (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Weighted average number of shares outstanding - basic	33,838	33,309	33,640	33,142
Stock options	271	207	279	156
Non-vested stock and stock units	254	307	336	401
Weighted average number of shares outstanding - diluted	34,363	33,823	34,255	33,699
Anti-dilutive securities	337	204	279	254