Recent Accounting Guidance (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue:
Revenue	$ 122,185
Gross profit	47,156	$ 34,714
Income from operations	18,502	10,713
Income before income taxes	17,473	9,517
Income tax provision	3,558	11
Net income	$ 13,915	$ 9,506
Net income per share:
Basic (in dollars per share)	$ 0.43	$ 0.32
Diluted (in dollars per share)	$ 0.41	$ 0.29
Consolidated Balance Sheet
Deferred income taxes	$ 80,697			$ 83,148
Total assets	505,144			488,218
Deferred revenue	18,522	$ 13,121		18,145
Total current liabilities	77,084			79,287
Total liabilities	133,617			134,608
Retained Earnings (Accumulated Deficit)	(189,230)			(204,745)
Total stockholders' equity	371,527			353,610
Total liabilities and stockholders' equity	505,144			488,218
Cumulative adjustment in deferred revenue				$ (5,000)
Product
Revenue:
Revenue	116,022
ASC 606 Adjustments
Revenue:
Revenue	(1,006)
Gross profit	(1,006)
Income from operations	(1,006)
Income before income taxes	(1,006)
Income tax provision	(232)
Net income	$ (774)
Net income per share:
Basic (in dollars per share)	$ (0.02)
Diluted (in dollars per share)	$ (0.02)
Consolidated Balance Sheet
Deferred income taxes	$ 232
Total assets	232
Deferred revenue	2,606
Total current liabilities	2,606
Total liabilities	2,606
Retained Earnings (Accumulated Deficit)	(2,374)
Total stockholders' equity	(2,374)
Total liabilities and stockholders' equity	232
ASC 606 Adjustments | Product
Revenue:
Revenue	(1,006)
ASC 606 Adjustments | ASU 2014-09
Consolidated Balance Sheet
Cumulative adjustment increase in retained earnings			$ 1,600
Cumulative adjustment in deferred revenue			$ 1,600
Before Topic 606
Revenue:
Revenue	121,179	$ 86,893
Gross profit	46,150
Income from operations	17,496
Income before income taxes	16,467
Income tax provision	3,326
Net income	$ 13,141
Net income per share:
Basic (in dollars per share)	$ 0.41
Diluted (in dollars per share)	$ 0.39
Consolidated Balance Sheet
Deferred income taxes	$ 80,929
Total assets	505,376
Deferred revenue	21,128
Total current liabilities	79,690
Total liabilities	136,223
Retained Earnings (Accumulated Deficit)	(191,604)
Total stockholders' equity	369,153
Total liabilities and stockholders' equity	505,376
Before Topic 606 | Product
Revenue:
Revenue	$ 115,016