Investment Securities (Narrative) (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014 Securities	Dec. 31, 2013 Securities	Jun. 30, 2013	Dec. 31, 2012
Investment [Line Items]
Non-marketable FHLB and FRB stock held for debt and regulatory purposes	$ 46,500,000	$ 46,500,000
Non-marketable private equity investments held	47,100,000	60,700,000
U.S. Treasury inflation-protected securities held	518,700,000
Percentage decrease requiring a review for impairment	20.00%
Fair value of securities on other-than-temporary impairment watch list	171,700,000	188,800,000
Credit-related portion of impairments included in earnings, for securities on watch list	13,410,000	12,499,000	12,196,000	11,306,000
Number of individual securities held in the available for sale portfolio	1,900
Securities in Unrealized Loss Positions, Number of Positions	297	507
Fair value of securities in an unrealized loss position	1,994,725,000	3,433,325,000
AFS securities in loss position at period-end, change in unrealized loss	71,400,000
Cumulative unrealized loss on securities in an unrealized loss position	46,769,000	118,178,000
Minimum period that OTTI securities have been in a loss position	12 months
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,508,542,000	421,202,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Percent of Portfolio	16.30%
Securities pledged as collateral	5,100,000,000
Securities pledged as collateral and may be sold or re-pledged	652,000,000
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]
Auction rate securities held at fair value	132,100,000
Fair value of securities in an unrealized loss position	487,064,000	656,968,000
Cumulative unrealized loss on securities in an unrealized loss position	12,823,000	33,345,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	355,533,000	178,150,000
Unrealized losses included in auction rate securities held	6,000,000
Unrealized losses included in other state and municipal obligations held	6,900,000
Aggregate fair value of state and municipal obligations excluding auction rate securities	1,700,000,000
State and municipal obligation portfolio, excluding auction rate securities, as a percentage of total available for sale securities	18.00%
Equity Securities [Member]
Investment [Line Items]
Common stock held by the holding company	44,900,000
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Fair value of securities on other-than-temporary impairment watch list	62,000,000
Credit-related portion of impairments included in earnings, for securities on watch list	13,400,000
Fair value of securities in an unrealized loss position	80,776,000	75,743,000
Cumulative unrealized loss on securities in an unrealized loss position	667,000	1,620,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 43,762,000	$ 22,289,000