Quarterly Financial Data (Unaudited) - Condensed Summary of Actual Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 184,692	$ 202,729	$ 217,617	$ 220,303	$ 211,874	$ 213,802	$ 215,996	$ 198,071	$ 825,341	$ 839,743	$ 747,718
Gross Profit	24,352	27,890	29,506	29,074	26,773	28,426	28,185	24,304	110,822	107,688	79,729
Operating Income	5,294	9,946	11,588	11,198	9,494	9,705	9,047	5,448	38,026	33,693	6,438
Net income (loss)	(2,291)	2,554	3,205	3,593	4,237	1,163	2,739	(508)	7,061	7,631	(12,451)
Net Income (Loss) Attributable to Common Stockholders	$ (2,291)	$ 2,554	$ 3,205	$ 3,592	$ 4,235	$ 1,162	$ 2,739	$ (506)	$ 7,060	$ 7,630	$ (12,445)
Basic Earnings (Loss) Per Share	$ (0.08)	$ 0.09	$ 0.11	$ 0.12	$ 0.15	$ 0.04	$ 0.09	$ (0.02)	$ 0.24	$ 0.26	$ (0.44)
Diluted Earnings (Loss) Per Share Attributable to Common Stockholders1	$ (0.08)	$ 0.09	$ 0.11	$ 0.12	$ 0.15	$ 0.04	$ 0.09	$ (0.02)	$ 0.24	$ 0.26	$ (0.44)