Acquisitions - SinfoniaRx (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 06, 2017 USD ($) D $ / shares shares	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
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
SinfoniaRx
Acquisition
Cash consideration	$ 35,000
Percentage of contingent consideration payable in cash	50.00%
Percentage of contingent consideration payable in stock	50.00%
Aggregate value of contingent consideration	$ 130,000
Contingent purchase price consideration earned or paid						$ 0
Issuance of common stock (in shares) | shares	520,821
Issuance price (in dollars per share) | $ / shares	$ 19.20
Number of trading days | D	20
Acquisition and integration costs		11		$ 72		$ 1,015
Purchase price consideration
Cash consideration at closing, net of adjustments	$ 34,492
Stock consideration at closing	11,541
Estimated fair value of contingent consideration	38,092
Total fair value of acquisition consideration	$ 84,125
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Cash		218		218
Accounts receivable		8,309		8,309
Prepaid expenses and other current assets		1,056		1,056
Property and equipment		1,419		1,419
Other assets		127		127
Goodwill		52,507		52,507
Total assets acquired		106,720		106,720
Accrued expenses and other liabilities		(3,819)		(3,819)
Trade accounts payable		(8,868)		(8,868)
Debt assumed		(675)		(675)
Deferred income tax liability, net		(9,233)		(9,233)
Total purchase price, including contingent consideration		84,125		84,125
Contingent consideration		38,092		38,092
Weighted average amortization period	7 years 3 months 29 days
SinfoniaRx | Maximum
Acquisition
Cash consideration	$ 35,000
SinfoniaRx | Trade name
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		4,776		4,776
Weighted average amortization period	10 years
SinfoniaRx | Developed technology
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		13,291		13,291
Weighted average amortization period	7 years
SinfoniaRx | Client relationships intangible asset
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		20,265		20,265
Weighted average amortization period	7 years 5 months 16 days
SinfoniaRx | Non-competition agreement
Allocation of the purchase price based on the estimated fair values of the assets acquired and liabilities assumed
Intangible assets		$ 4,752		$ 4,752
Weighted average amortization period	5 years