Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Commitments to fund additional investments in nonmarketable equity securities	$ 5
Nonrecurring
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Commitments to fund additional investments in nonmarketable equity securities	0		0
Nonrecurring | Level 3
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans	64		128
Nonmarketable equity securities	2	[1]	2	[1]
Other real estate	2		5
Total assets at fair value	68		135
Nonrecurring | Level 3 | Commercial
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans	38		43
Nonrecurring | Level 3 | Real estate construction
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans			20
Nonrecurring | Level 3 | Commercial mortgage
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans	26		61
Nonrecurring | Level 3 | International
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans			$ 4

[1] Commitments to fund additional investments in nonmarketable equity securities recorded at fair value on a nonrecurring basis were insignificant at December 31, 2014 and 2013.