CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 78,111	$ 84,398	$ 221,187	$ 174,679
Other comprehensive income:
Foreign currency translation gain (loss)	1,185	(2,142)	797	(983)
Defined benefit pension plan:
Prior service cost arising during period, net of tax				(1,010)
Actuarial gain arising during period, net of tax			64	186
Less: amortization of actuarial gain and prior service cost included in net periodic pension cost	131	144	391	403
Defined benefit pension plan, net	131	144	455	(421)
Unrealized gain (loss) on available-for-sale securities, net of tax	72	(119)	109	(62)
Other comprehensive income (loss), net of tax	1,388	(2,117)	1,361	(1,466)
Comprehensive income	$ 79,499	$ 82,281	$ 222,548	$ 173,213