Condensed Consolidated Statements of Comprehensive Income (Unaudited) - 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	$ 163,320	$ 88,099	$ 262,006	$ 203,657
Other comprehensive income, net of tax:
Foreign currency translation adjustment	(4,209)	253	(4,429)	760
Unrealized holding gain on available-for-sale securities	7	21	69	37
Pension and postretirement liability adjustment	387	171	1,001	314
Total other comprehensive (loss) income	(3,815)	445	(3,359)	1,111
Comprehensive income	$ 159,505	$ 88,544	$ 258,647	$ 204,768