Acquired Property Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Acquired Property [Roll Forward]
Beginning balance - Acquired property	$ 9,199	$ 12,296	$ 11,442	$ 12,307
Additions - Acquired property	2,236	3,240	7,602	10,437
Disposals - Acquired property	(3,125)	(3,412)	(10,734)	(10,620)
Ending balance - Acquired property	8,310	12,124	8,310	12,124
Real Estate Owned Valuation Allowance [Roll Forward]
Beginning balance - Valuation allowance	(693)	(736)	(824)	(686)
Decrease (increase) in Valuation allowance	74	(49)	205	(99)
Ending balance - Valuation allowance	(619)	(785)	(619)	(785)
Ending balance - Acquired property, net	$ 7,691	$ 11,339	$ 7,691	$ 11,339	$ 10,618