Troubled Debt Restructures and Nonperforming Receivables - Additional Information on Nonaccrual Receivables (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Interest income that would have been recorded if the nonaccrual receivable had been current in accordance with contractual terms during the period		$ 8	$ 18
Interest income that was recorded on nonaccrual receivables during the period (less than $1 million for the period ended March 31, 2017)	[1]	0	$ 2
Maximum [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Interest income that was recorded on nonaccrual receivables during the period (less than $1 million for the period ended March 31, 2017)		$ 1

[1] During the three months ended March 31, 2017, interest income recorded on nonaccrual receivables was less than $1 million.