Business Changes and Accounting Developments (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended		3 Months Ended		6 Months Ended	0 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Flagstar	Jun. 30, 2013 Common Stock	Mar. 31, 2013 Common Stock	Jun. 30, 2013 Common Stock	Jun. 05, 2013 Common Stock WL Ross & Co. LLC and its Affiliates
Significant Transactions [Line Items]
Stock repurchase program, total authorized amount					$ 315
Common stock repurchases (in shares)			9,600,000	1,900,000		5,000,000
Common stock repurchases	244.0		205.0	39.0		109.7
Number of shares held by related party						14,900,000
Percentage of ownership by related party						8.00%
Previous percentage of ownership by related party						10.50%
Remaining authorized repurchase amount under stock repurchase program	71
Proceeds from legal settlements		$ 105