Employee Benefit Plans (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2007 years	Dec. 31, 2005 years
Defined Benefit Plan Disclosure [Line Items]
Proceeds from stock option exercises	$ 7,438,000	$ 38,807,000	$ 16,226,000
Shares issued in connection with stock compensation awards	140,739	666,222
Issuance of treasury stock, shares	29,824	176,991
Expense related to benefit plans	11,800,000	12,000,000	12,100,000
Expected to recognize net actuarial gain (loss)	5,700,000
Investment in equity securities, percentage	62.00%
Investment in fixed income debt securities, percentage	35.00%
End-of-year contribution to the plan	5,000,000
Modeling process confidence ratio	90.00%
Percentage of equity investments in mutual fund	67.00%
Assumed long-term rate of return	8.25%
Minimum cash collateral provided by brokers on fair value of securities borrowed	100.00%
Minimum non-cash collateral provided by brokers on fair value of securities borrowed	102.00%
Expected defined benefit plans	1,000,000
Target percentage of pay at age 55	45.00%
Target percentage of pay at age 60	60.00%
Contribution match by employer	100.00%
Participants contribution eligible for match	6.00%
Stock purchase plan expense	10,834,000	9,839,000	9,314,000
Life period of options awarded, years				6	10
Vesting period of options awarded, years				four	four
Maximum exercise period for exceeding of options granted, years	10
Awards other than in the form of stock options	174,105
Intrinsic value of outstanding in-the-money stock options	10,500,000
Total intrinsic value of stock options exercised	1,500,000	6,600,000	4,900,000
Outstanding in-the-money exercisable stock options	5,400,000
Total fair value of stock awards/stock units vested	6,200,000	3,300,000	2,600,000
Weighted-average period, unrecognized expense related to stock options, years	2.7
Weighted-average period, unrecognized expense related to non-vested stock awards, years	2.7
Weighted-average fair value of stock options granted	$ 9.78	$ 12.94	$ 14.43
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution percentage of eligible compensation	50
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution percentage of eligible compensation	2
401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Stock purchase plan expense	$ 10,200,000	$ 9,800,000	$ 9,800,000