Income Taxes - Additional Information (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets, carryforwards
Operating loss carry forward	$ 81,000,000
Tax credit carry forwards	123,000,000
Net valuation allowance	0
Income Tax Uncertainties [Abstract]
Unrecognized tax positions that would affect the effective tax rate	11,000,000	$ 8,000,000	$ 11,000,000
Interest and penalties accrued	$ 0	$ 0	$ 1,000,000