Derivative Instruments, Hedging Activities and Fair Value (Details 3) (USD $)	3 Months Ended		9 Months Ended			12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Foreign currency forward exchange contracts	Dec. 31, 2011 Foreign currency forward exchange contracts	Sep. 30, 2012 British pounds sterling Commitments to sell foreign currencies	Dec. 31, 2011 British pounds sterling Commitments to sell foreign currencies	Sep. 30, 2012 British pounds sterling Commitments to purchase foreign currencies	Dec. 31, 2011 British pounds sterling Commitments to purchase foreign currencies	Sep. 30, 2012 Euros Commitments to sell foreign currencies	Dec. 31, 2011 Euros Commitments to sell foreign currencies	Sep. 30, 2012 Euros Commitments to purchase foreign currencies	Dec. 31, 2011 Euros Commitments to purchase foreign currencies	Sep. 30, 2012 Other currencies Commitments to sell foreign currencies	Dec. 31, 2011 Other currencies Commitments to sell foreign currencies	Sep. 30, 2012 Other currencies Commitments to purchase foreign currencies	Dec. 31, 2011 Other currencies Commitments to purchase foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent					$ 396,410,000	$ 324,463,000	$ 1,457,000	$ 18,350,000	$ 1,711,000	$ 4,364,000	$ 236,054,000	$ 178,889,000	$ 106,601,000	$ 105,247,000	$ 2,485,000	$ 2,957,000	$ 48,102,000	$ 14,656,000
Recognized Gain (Loss)					(2,169,000)	1,732,000	(6,000)	(20,000)	1,000	(12,000)	(2,362,000)	2,345,000	12,000	(878,000)	(32,000)	62,000	218,000	235,000
Pre-tax net gains (losses) on certain loans designated as hedges of net investments in foreign subsidiaries	$ (1,900,000)	$ 5,500,000	$ (4,400,000)	$ (3,700,000)