Shareholders' Equity (Details Textuals) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Stockholders' Equity (Textuals) [Abstract]
Pretax unrealized gains (losses) related to credit-only impaired securities	$ 1			$ 1		$ (17)
Net of tax unrealized gains (losses) related to credit-only impaired securities						(11)
Restricted Common Stock, shares issued				131,955
Restricted Common Stock, fair value per share				$ 34.34
Common Stock issued, fair value per share		$ 33.99
Fair value per share of options granted				$ 12.49
Expected dividend yield				1.90%
Expected volatility				38.00%
Expected term				7.3
Risk-free rate				3.04%
Total share based compensation	$ 5		$ 5	$ 10	$ 10
Voting Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, shares authorized	12,500,000			12,500,000
Preferred Stock, par value	$ 0			$ 0
Nonvoting Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, shares authorized	12,500,000			12,500,000
Preferred Stock, par value	$ 0			$ 0
Stock incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock options issued under stock incentive plan, average exercise price	$ 34.34			$ 34.34
Common Stock options issued under stock incentive plan				1,100,000
Annual Co-CEO Equity Bonus Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other benefit plans, shares		188,302