Investment Securities (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 Securities Investments_In_Single_Issuer	Dec. 31, 2012 Securities
Investment [Line Items]
Non-marketable FHLB and FRB stock held for debt and regulatory purposes	$ 46,500,000	$ 45,400,000
Non-marketable private equity investments held	60,700,000	73,200,000
U.S. Treasury inflation-protected securities held	505,600,000
Common stock classified as equity securities held by the holding company	37,200,000
Percentage decrease requiring a review for impairment	20.00%
Fair Value Of Securities With O T T I For Loss Position Twelve Months	0
Fair value of securities on other-than-temporary impairment watch list	188,800,000	220,700,000
Aggregate fair value of non-agency mortgage backed securities with other-than-temporary impairment	70,400,000
Credit-related portion of impairments included in earnings	12,800,000
Number of individual securities held in the available for sale portfolio	1,800
Number of individual securities held in the available for sale portfolio in a loss position	507	144
Portfolio securities aggregate fair value loss position	3,433,325,000	901,882,000
Available for sale securities in loss position at period end, change in unrealized loss	98,000,000
Available for sale securities, Continuous Unrealized Loss Position, Aggregate Loss	118,178,000	20,171,000
Fair value of securities in loss position for twelve months or longer	421,202,000	171,823,000
Fair value of securities in a loss position for 12 months or longer, as a percentage of total available for sale portfolio	4.70%
Gross unrealized losses included in state and municipal obligation holdings	33,300,000
Securities pledged as collateral	5,000,000,000	4,300,000,000
Securities pledged as collateral and may be sold or re-pledged	687,700,000
Number of investments in a single issuer that exceed 10% of stockholder's equity	0
No investment in a single issuer exceeds this percentage of stockholder's equity	10.00%
State and municipal obligations [Member]
Investment [Line Items]
Aggregate fair value of state and municipal obligations excluding auction rate securities	1,500,000,000
Auction rate securities held at fair value	127,700,000
Portfolio securities aggregate fair value loss position	656,968,000	254,130,000
Available for sale securities, Continuous Unrealized Loss Position, Aggregate Loss	33,345,000	16,295,000
Fair value of securities in loss position for twelve months or longer	178,150,000	80,530,000
Unrealized losses included in auction rate securities held	10,000,000
Unrealized losses included in other state and municipal obligations held	$ 23,300,000
State and municipal obligation portfolio, excluding auction rate securities, as a percentage of total available for sale securities	16.70%