CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 3,642	$ 2,365
Other comprehensive income:
Realized losses on short-term investments reclassified from accumulated other comprehensive income, net of tax of $0 and $1, respectively		3
Net change in unrealized gains and (losses) on available-for-sale investments, net of tax of $138 and $560, respectively	176	2,385
Comprehensive income	$ 3,818	$ 4,753