CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Balance at beginning of period at Dec. 31, 2017	$ 2	$ (959)	$ 144,074	$ (19,229)	$ 123,888
Balance at beginning of period (in shares) at Dec. 31, 2017	19,371,005	(73,466)
Increase (Decrease) in Stockholders' Equity
Common stock offering issuance costs			(2)		(2)
Issuance of restricted stock (in shares)	395,254
Forfeitures of restricted shares (in shares)		(2,474)
Shares repurchased		$ (2,866)			(2,866)
Shares repurchased (in shares)		(80,000)
Exercise of stock options			902		902
Exercise of stock options (in shares)	374,904
Stock based compensation expense			1,945		1,945
Net (loss) income				(18,094)	(18,094)
Balance at end of period at Mar. 31, 2018	$ 2	$ (3,825)	146,919	(37,323)	105,773
Balance at end of period (in shares) at Mar. 31, 2018	20,141,163	(155,940)
Balance at beginning of period at Dec. 31, 2017	$ 2	$ (959)	144,074	(19,229)	123,888
Balance at beginning of period (in shares) at Dec. 31, 2017	19,371,005	(73,466)
Increase (Decrease) in Stockholders' Equity
Shares repurchased		$ (2,866)
Shares repurchased (in shares)		(80,000)
Net (loss) income					(36,704)
Balance at end of period at Sep. 30, 2018	$ 2	$ (3,825)	157,353	(55,933)	97,597
Balance at end of period (in shares) at Sep. 30, 2018	20,512,499	(155,940)
Balance at beginning of period at Mar. 31, 2018	$ 2	$ (3,825)	146,919	(37,323)	105,773
Balance at beginning of period (in shares) at Mar. 31, 2018	20,141,163	(155,940)
Increase (Decrease) in Stockholders' Equity
Issuance of restricted stock (in shares)	23,365
Exercise of stock options			1,253		1,253
Exercise of stock options (in shares)	216,989
Stock based compensation expense			2,180		2,180
Net (loss) income				(29,026)	(29,026)
Balance at end of period at Jun. 30, 2018	$ 2	$ (3,825)	150,352	(66,349)	80,180
Balance at end of period (in shares) at Jun. 30, 2018	20,381,517	(155,940)
Increase (Decrease) in Stockholders' Equity
Common stock offering issuance costs			(7)		(7)
Issuance of common stock in connection with acquisition			3,595		3,595
Issuance of common stock in connection with acquisition (in shares)	45,561
Issuance of restricted stock (in shares)	14,840
Exercise of stock options			417		417
Exercise of stock options (in shares)	70,581
Stock based compensation expense			2,996		2,996
Net (loss) income				10,416	10,416
Balance at end of period at Sep. 30, 2018	$ 2	$ (3,825)	157,353	(55,933)	97,597
Balance at end of period (in shares) at Sep. 30, 2018	20,512,499	(155,940)
Balance at beginning of period at Dec. 31, 2018	$ 2	$ (3,825)	209,330	(66,498)	139,009
Balance at beginning of period (in shares) at Dec. 31, 2018	20,719,297	(161,760)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in connection with acquisition			9,504		9,504
Issuance of common stock in connection with acquisition (in shares)	149,053
Issuance of common stock awards (in shares)	9,547
Issuance of restricted stock (in shares)	565,840
Exercise of stock options		$ (40)	1,077		1,037
Exercise of stock options (in shares)	82,686	(690)
Issuance of common stock in connection with the settlement of acquisition-related contingent consideration			(609)		(609)
Issuance of common stock in connection with the settlement of acquisition-related contingent consideration (in shares)	614,225
Conversion feature of convertible senior subordinated notes, net of allocated debt issuance costs, net of tax			74,049		74,049
Purchase of convertible note hedges			(101,660)		(101,660)
Sale of warrants in connection with convertible senior subordinated notes			65,910		65,910
Stock based compensation expense			6,852		6,852
Net (loss) income				(10,979)	(10,979)
Balance at end of period at Mar. 31, 2019	$ 2	$ (3,865)	264,453	(77,477)	183,113
Balance at end of period (in shares) at Mar. 31, 2019	22,140,648	(162,450)
Balance at beginning of period at Dec. 31, 2018	$ 2	$ (3,825)	209,330	(66,498)	139,009
Balance at beginning of period (in shares) at Dec. 31, 2018	20,719,297	(161,760)
Increase (Decrease) in Stockholders' Equity
Net (loss) income					(25,612)
Balance at end of period at Sep. 30, 2019	$ 2	$ (3,865)	280,739	(92,110)	184,766
Balance at end of period (in shares) at Sep. 30, 2019	22,354,559	(162,450)
Balance at beginning of period at Mar. 31, 2019	$ 2	$ (3,865)	264,453	(77,477)	183,113
Balance at beginning of period (in shares) at Mar. 31, 2019	22,140,648	(162,450)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock awards (in shares)	30,101
Issuance of restricted stock (in shares)	23,562
Exercise of stock options			499		499
Exercise of stock options (in shares)	49,916
Conversion feature of convertible senior subordinated notes, net of allocated debt issuance costs, net of tax			(47)		(47)
Stock based compensation expense			6,906		6,906
Net (loss) income				(6,529)	(6,529)
Balance at end of period at Jun. 30, 2019	$ 2	$ (3,865)	271,811	(84,006)	183,942
Balance at end of period (in shares) at Jun. 30, 2019	22,244,227	(162,450)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock awards (in shares)	13,867
Exercise of stock options			967		967
Exercise of stock options (in shares)	96,465
Conversion feature of convertible senior subordinated notes, net of allocated debt issuance costs, net of tax			736		736
Stock based compensation expense			7,225		7,225
Net (loss) income				(8,104)	(8,104)
Balance at end of period at Sep. 30, 2019	$ 2	$ (3,865)	$ 280,739	$ (92,110)	$ 184,766
Balance at end of period (in shares) at Sep. 30, 2019	22,354,559	(162,450)