Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current Fiscal Year End Date									--12-31
Current Federal Tax Expense (Benefit)									$ 42,934	$ 43,632	$ 38,704
Current Foreign Tax Expense (Benefit)									20,965	11,515	30,357
Current State and Local Tax Expense (Benefit)									4,344	5,600	4,821
Current Income Tax Expense (Benefit)									68,243	60,747	73,882
Deferred Federal Income Tax Expense (Benefit)									963	(8,905)	(9,699)
Deferred Foreign Income Tax Expense (Benefit)									2,677	2,892	100
Deferred State and Local Income Tax Expense (Benefit)									(35)	(536)	(536)
Deferred Income Tax Expense (Benefit)									3,605	(6,549)	(10,135)
Income Tax Expense (Benefit)	$ 18,394	$ 18,671	$ 16,997	$ 17,786	$ 17,371	$ 14,599	$ 14,710	$ 7,518	$ 71,848	$ 54,198	$ 63,747