Business Combinations - Summary of Estimated Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands		6 Months Ended
	Jan. 05, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 148,031		$ 107,086
Less seller obligations		3,025	$ 2,430
Alpha [Member]
Business Acquisition [Line Items]
Cash		247
Accounts receivable		30,405
Inventories		1,751
Other current assets		5,566
Property and equipment		1,528
Intangibles		57,100
Goodwill		37,825
Other non-current assets		150
Accounts payable and other current liabilities		(17,901)
Fair value of assets acquired and purchase price		116,671
Less fair value of common stock issued		10,859
Less seller obligations		2,002
Cash paid	$ 103,800	103,810
Columbia [Member]
Business Acquisition [Line Items]
Accounts receivable		990
Inventories		650
Property and equipment		659
Intangibles		4,760
Goodwill		1,699
Other non-current assets		31
Accounts payable and other current liabilities		(348)
Fair value of assets acquired and purchase price		8,441
Less seller obligations		623
Cash paid		7,818
Other Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable		1,130	1,518
Inventories		880	311
Other current assets		3	8
Property and equipment		686	789
Intangibles		3,321	5,036
Goodwill		963	3,220
Other non-current assets		129	24
Accounts payable and other current liabilities		(1,210)	(1,239)
Fair value of assets acquired and purchase price		5,902	9,667
Less seller obligations		400	870
Cash paid		5,502	8,797
Combined Business Acquisitions [Member]
Business Acquisition [Line Items]
Cash		247
Accounts receivable		32,525	5,477
Inventories		3,281	1,011
Other current assets		5,569	8
Property and equipment		2,873	1,445
Intangibles		65,181	17,836
Goodwill		40,487	9,862
Other non-current assets		310	24
Accounts payable and other current liabilities		(19,459)	(3,285)
Fair value of assets acquired and purchase price		131,014	32,378
Less fair value of common stock issued		10,859
Less seller obligations		3,025	2,430
Cash paid		$ 117,130	29,948
Alpine [Member]
Business Acquisition [Line Items]
Accounts receivable			3,959
Inventories			700
Property and equipment			656
Intangibles			12,800
Goodwill			6,642
Accounts payable and other current liabilities			(2,046)
Fair value of assets acquired and purchase price			22,711
Less seller obligations			1,560
Cash paid			$ 21,151