Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 651,639	$ 340,074	$ 174,560
Other comprehensive (loss) income:
Foreign currency translation loss	(5,296)	(4,789)	(1,193)
Defined benefit pension plan:
Prior service cost arising during period, net of tax		(2,415)
Actuarial gain (loss) arising during period, net of tax	826	2,999	2,075
Less: amortization of actuarial gain and prior service cost included in net periodic pension cost, net of tax	877	904	1,020
Total defined benefit pension plan, net	1,703	1,488	3,095
Unrealized loss gain on available-for-sale securities, net of tax	(74)	(250)	(128)
Other comprehensive (loss) gain, net of tax	(3,667)	(3,551)	1,774
Comprehensive income	$ 647,972	$ 336,523	$ 176,334