Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income	$ 19,174	$ 23,469	$ 48,672	$ 42,904
Available-for-sale marketable securities:
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Reclassification Adjustments, after Tax	40	(85)	1,419	(427)
Reclassification adjustment for net realized gain (loss) included in net income	(18)	154	25	249
Change in net unrealized gain (loss) on marketable securities, net of tax	22	69	1,444	(178)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	27	0	(10)	0
Total change in unrealized gain (loss) on cash flow hedges, net of tax	1,009	0	1,413	0
Other comprehensive income (loss), net of tax	1,031	69	2,857	(178)
Comprehensive income	20,205	23,538	51,529	42,726
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Available-for-sale marketable securities:
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	$ 982	$ 0	$ 1,423	$ 0