Acquisitions - Peak PACE Solutions (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	May 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Goodwill		$ 90,919		$ 90,919		$ 74,613
Revenue		54,418	$ 32,731	146,960	$ 90,145
Net income		10,416	$ 6,165	$ (36,704)	$ 1,889
Trade name
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Weighted average amortization period				8 years 18 days		8 years 6 months 22 days
Developed technology
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Weighted average amortization period				7 years 7 days		7 years 4 months 17 days
Non-competition agreement
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Weighted average amortization period				6 years 11 months 27 days		4 years 11 months 16 days
Peak PACE Solutions
Acquisition
Cash consideration	$ 7,719
Acquisition and integration costs		7		$ 269
Purchase price consideration
Cash consideration at closing, net of post-closing adjustments	7,563
Estimated fair value of contingent consideration	1,620
Total fair value of acquisition consideration	$ 9,183
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Cash		606		606
Property and equipment		84		84
Goodwill		3,559		3,559
Total assets acquired		9,809		9,809
Accrued expenses and other liabilities		(626)		(626)
Total purchase price, including contingent consideration		9,183		9,183
Contingent consideration		1,620		1,620
Weighted average amortization period	9 years 6 months 4 days
Revenue		$ 2,330		$ 3,679
Type of Revenue [Extensible List]		Service [Member]		Service [Member]
Net income		$ 479		$ 254
Peak PACE Solutions | Maximum
Purchase price consideration
Total fair value of acquisition consideration	$ 10,000
Peak PACE Solutions | Trade name
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		290		290
Weighted average amortization period	1 year 6 months
Peak PACE Solutions | Client relationships intangible asset
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		5,220		5,220
Weighted average amortization period	10 years
Peak PACE Solutions | Non-competition agreement
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		$ 50		$ 50
Weighted average amortization period	5 years