Derivative Instruments, Hedging Activities and Fair Value (Details 3) (USD $)	3 Months Ended			12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign currency forward exchange contracts	Mar. 31, 2013 Foreign Currency Buy [Member] British pounds sterling Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign Currency Buy [Member] British pounds sterling Foreign currency forward exchange contracts	Mar. 31, 2013 Foreign Currency Buy [Member] Euros Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign Currency Buy [Member] Euros Foreign currency forward exchange contracts	Mar. 31, 2013 Foreign Currency Buy [Member] Other currencies Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign Currency Buy [Member] Other currencies Foreign currency forward exchange contracts	Mar. 31, 2013 Foreign Currency Sell [Member] British pounds sterling Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign Currency Sell [Member] British pounds sterling Foreign currency forward exchange contracts	Mar. 31, 2013 Foreign Currency Sell [Member] Euros Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign Currency Sell [Member] Euros Foreign currency forward exchange contracts	Mar. 31, 2013 Foreign Currency Sell [Member] Other currencies Foreign currency forward exchange contracts	Dec. 31, 2012 Foreign Currency Sell [Member] Other currencies Foreign currency forward exchange contracts
Foreign Currency Derivatives
U.S. Dollar Equivalent			$ 399,879,000	$ 434,095,000	$ 7,092,000	$ 6,141,000	$ 129,970,000	$ 116,618,000	$ 53,456,000	$ 44,291,000	$ 3,079,000	$ 0	$ 203,335,000	$ 264,234,000	$ 2,947,000	$ 2,811,000
Recognized Gain (Loss)			(1,471,000)	(923,000)	11,000	58,000	(3,208,000)	187,000	41,000	(71,000)	(4,000)	0	1,698,000	(1,082,000)	(9,000)	(15,000)
Pre-tax net gains (losses) on certain loans designated as hedges of net investments in foreign subsidiaries	$ (1,700,000)	$ 6,700,000