CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 42,602	$ 32,042	$ 69,059	$ 55,569
Other comprehensive (loss) income, net:
Amortization of actuarial loss on defined benefit pension plan, net	4	4	72	9
Unrealized (loss) gain on marketable securities, available-for-sale, net	(150)	236	(169)	424
Other comprehensive (loss) income, net	(146)	240	(97)	433
Comprehensive income	$ 42,456	$ 32,282	$ 68,962	$ 56,002