Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Assets Measured at Fair Value on a Nonrecurring Basis
Impaired loans	$ 149	$ 219
Loans held for sale	15	15
Direct financing leases and operating lease assets held for sale	0	0
Goodwill and other intangible assets	0	0
Accrued income and other assets	0	62
Other investments	44	0
Total assets on a nonrecurring basis at fair value	208	296
Additional Fair Value Measurements (Textual)
Transfer of commercial and consumer loans from held-for-sale to held-to-maturity, current fair value	28
Average maturity of short term financial instrument	less than six months
Level 1 [Member]
Assets Measured at Fair Value on a Nonrecurring Basis
Impaired loans	0	0
Loans held for sale	0	0
Direct financing leases and operating lease assets held for sale	0	0
Goodwill and other intangible assets	0	0
Accrued income and other assets	0	0
Other investments	0	0
Total assets on a nonrecurring basis at fair value	0	0
Level 2 [Member]
Assets Measured at Fair Value on a Nonrecurring Basis
Impaired loans	0	0
Loans held for sale	0	0
Direct financing leases and operating lease assets held for sale	0	0
Goodwill and other intangible assets	0	0
Accrued income and other assets	0	39
Other investments	19	0
Total assets on a nonrecurring basis at fair value	19	39
Level 3 [Member]
Assets Measured at Fair Value on a Nonrecurring Basis
Impaired loans	149	219
Loans held for sale	15	15
Direct financing leases and operating lease assets held for sale	0	0
Goodwill and other intangible assets	0	0
Accrued income and other assets	0	23
Other investments	25	0
Total assets on a nonrecurring basis at fair value	$ 189	$ 257