Summary of Significant Accounting Policies Regulatory Capital (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Capital Reserve Amount, Fiscal Year, Senior Preferred Stock Purchase Agreement, September 2019 Amendment [Line Items]
Deficit of core capital over statutory minimum capital requirement	$ (133,800)	$ (137,100)
US Treasury [Member]
Capital Reserve Amount, Fiscal Year, Senior Preferred Stock Purchase Agreement, September 2019 Amendment [Line Items]
Capital Reserve Amount Fiscal Year Senior Preferred Stock Purchase Agreement September 2019 Amendment	$ 22,000