Goodwill and Other Intangible Assets - Estimated Aggregate Pre-Tax Amortization Expense Related to Intangible Assets (Details) $ in Millions	Mar. 31, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense remainder of 2018	$ 7
Amortization expense 2019	8
Amortization expense 2020	7
Amortization expense 2021	7
Amortization expense 2022	$ 7