CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income and Comprehensive Income [Abstract]
Net income	$ 39,388	$ 35,076
Other comprehensive income (loss), net of taxes:
Pension adjustment	84	124
Foreign currency translation	(471)	(244)
Unrealized gain (loss) on securities and reclassification adjustments	(36)	(61)
Comprehensive income	$ 38,965	$ 34,895