Business Acquisitions - Total Purchase Price Allocation (Details) - USD ($) $ in Thousands			9 Months Ended		12 Months Ended
	Dec. 08, 2016	Jan. 05, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 334,780		$ 327,724
Total purchase price, net of cash received			$ 4,446	$ 271,458
Aesynt Holding, L.P., Aesynt, Ltd.
Business Acquisition [Line Items]
Cash		$ 8,164
Accounts receivable		43,312
Inventory		19,021
Other current assets		3,787
Total current assets		74,284
Property and equipment		10,389
Intangibles		123,700
Goodwill		163,599
Other non-current assets		968
Total assets		372,940
Current liabilities		26,753
Deferred revenue		25,512
Non-current deferred tax liabilities		38,622
Other non-current liabilities		2,431
Total liabilities		93,318
Total purchase price		279,622
Total purchase price, net of cash received		$ 271,458
Ateb
Business Acquisition [Line Items]
Cash	$ 902
Accounts receivable	7,761
Inventory	225
Other current assets	1,239
Total current assets	10,127
Property and equipment	2,447
Intangibles	12,500
Goodwill	21,651
Other non-current assets	334
Total assets	47,059
Current liabilities	2,314
Deferred revenue	2,776
Non-current deferred tax liabilities	0
Other non-current liabilities	367
Total liabilities	5,457
Total purchase price	41,602
Total purchase price, net of cash received	$ 40,700
2016 Acquisitions Aesynt and Ateb
Business Acquisition [Line Items]
Cash					9,066
Accounts receivable					51,073
Inventory					19,246
Other current assets					5,026
Total current assets					84,411
Property and equipment					12,836
Intangibles					136,200
Goodwill					185,250
Other non-current assets					1,302
Total assets					419,999
Current liabilities					29,067
Deferred revenue					28,288
Non-current deferred tax liabilities					38,622
Other non-current liabilities					2,798
Total liabilities					98,775
Total purchase price					321,224
Total purchase price, net of cash received					$ 312,158