Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Comprehensive Income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 75	$ 28
Total comprehensive income	112	270
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	44	226
Other comprehensive income (loss):
Change in net gain / loss on cash-flow hedging instruments	(7)	16
Total other comprehensive income	37	242
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Other comprehensive income (loss):
Total other comprehensive income		226
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other comprehensive income (loss):
Total other comprehensive income		16
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Other comprehensive income (loss):
Total other comprehensive income	$ 0	$ 0