Significant Accounting Policies - Accounting Changes (Details) $ in Millions |
12 Months Ended |
|---|---|
|
Dec. 31, 2016
USD ($)
| |
| ASU 2016-09 Improvements to Employee Share-Based Payment Accounting | Income Tax Benefit | |
| New Accounting Pronouncements or Change in Accounting Principle | |
| New accounting pronouncement income statement impact | $ 184 |