Income Taxes (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Valuation allowance	$ 311	$ 248
Deferred tax liability	6
Excess of financial reporting over the tax basis of investments not reinvested	81
Excess of financial reporting over the tax basis of investments to be reinvested	1,900
Total income tax provision	$ 80	$ 63	$ 84
Effective income tax rate	23.50%	15.60%	19.80%
Unrecognized tax benefits	$ 67	$ 47	$ 44	$ 30
Interest accrued for unrecognized tax benefits	$ 2