Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Apr. 01, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned		$ 0				$ 30,164				$ 0	$ 30,164	$ 0
Cash paid for acquisition										0	20,930	0
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed										514	786
Revenues		141,874	$ 108,348	$ 102,342	$ 146,296	104,567	$ 91,913	$ 92,682	$ 170,081	498,860	459,244	498,834
Net Income		11,863	$ 4,416	$ 8,029	$ 20,367	$ 8,619	$ 5,119	$ 6,294	$ 21,109	$ 44,675	41,140	$ 36,092
Gatherco [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares										592,970
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 30,200	30,164								$ 30,164
Cash paid for acquisition	27,500									27,494
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt	1,696	1,696								1,696
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	$ 6,800	6,806								6,806
Business Combination Contingent Cash Consideration Payable		$ 15,000								$ 15,000
Period Additional Contingent Cash Consideration Will Be Based On										5 years
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed										$ 1,300
Revenues										26,600	16,700
Net Income										$ 2,100	312
BravePoint Group [Member]
Revenues											15,100
Net Income											$ (232)