CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 16,251	$ 26,136	$ 18,616	$ 39,895
Other comprehensive income:
Realized losses on short-term investments reclassified from accumulated other comprehensive income, net of tax of ($1), $0, ($2), and $0, respectively			3
Net change in unrealized gains and (losses) on available-for-sale investments, net of tax of ($1,242), $0, ($1,802) and $0, respectively	133	(1,652)	2,518	(1,652)
Comprehensive income	$ 16,384	$ 24,484	$ 21,137	$ 38,243