Financial Instruments (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Foreign Currency Derivatives
Pre-tax net gains and losses on certain loans designated as hedges of net investments in foreign subsidiaries	$ (1,200,000)	$ 19,000,000
Foreign currency forward exchange contracts
Foreign Currency Derivatives
Maximum maturity period of unsecured contracts (in months)	10 months
U.S. Dollar Equivalent	324,463,000	214,151,000
Recognized Gain (Loss)	1,732,000	1,717,000
British pounds sterling | Commitments to sell foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent	18,350,000	54,479,000
Recognized Gain (Loss)	(20,000)	1,806,000
British pounds sterling | Commitments to purchase foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent	4,364,000	208,000
Recognized Gain (Loss)	(12,000)	(2,000)
Euros | Commitments to sell foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent	178,889,000	93,831,000
Recognized Gain (Loss)	2,345,000	(104,000)
Euros | Commitments to purchase foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent	105,247,000	44,571,000
Recognized Gain (Loss)	(878,000)	(338,000)
Other currencies | Commitments to sell foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent	2,957,000	5,314,000
Recognized Gain (Loss)	62,000	(86,000)
Other currencies | Commitments to purchase foreign currencies
Foreign Currency Derivatives
U.S. Dollar Equivalent	14,656,000	15,748,000
Recognized Gain (Loss)	$ 235,000	$ 441,000