Derivative Instruments, Hedging Activities and Fair Value (Details 3) (USD $)	3 Months Ended		6 Months Ended			12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Foreign currency forward exchange contracts	Dec. 31, 2011 Foreign currency forward exchange contracts	Jun. 30, 2012 British pounds sterling Commitments to sell foreign currencies	Dec. 31, 2011 British pounds sterling Commitments to sell foreign currencies	Jun. 30, 2012 British pounds sterling Commitments to purchase foreign currencies	Dec. 31, 2011 British pounds sterling Commitments to purchase foreign currencies	Jun. 30, 2012 Euros Commitments to sell foreign currencies	Dec. 31, 2011 Euros Commitments to sell foreign currencies	Jun. 30, 2012 Euros Commitments to purchase foreign currencies	Dec. 31, 2011 Euros Commitments to purchase foreign currencies	Jun. 30, 2012 Other currencies Commitments to sell foreign currencies	Dec. 31, 2011 Other currencies Commitments to sell foreign currencies	Jun. 30, 2012 Other currencies Commitments to purchase foreign currencies	Dec. 31, 2011 Other currencies Commitments to purchase foreign currencies
Foreign Currency Derivatives
Maximum maturity period of unsecured contracts (in months)	six		six
U.S. Dollar Equivalent					$ 346,400,000	$ 324,463,000	$ 3,577,000	$ 18,350,000	$ 2,215,000	$ 4,364,000	$ 194,376,000	$ 178,889,000	$ 106,313,000	$ 105,247,000	$ 2,558,000	$ 2,957,000	$ 37,361,000	$ 14,656,000
Recognized Gain (Loss)					(19,000)	1,732,000	20,000	(20,000)	(7,000)	(12,000)	879,000	2,345,000	(801,000)	(878,000)	7,000	62,000	(117,000)	235,000
Pre-tax net gains (losses) on certain loans designated as hedges of net investments in foreign subsidiaries	$ 2,500,000	$ (2,300,000)	$ 6,900,000	$ (9,200,000)