Fair Value Measurement - Fair Value of Assets (Liabilities) Not Measured at Fair Value In Consolidated Balance Sheet - Additional Information (Details) - USD ($) $ in Millions |
Sep. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Fixed-Rate Long-Term Debt | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Long term debt, carrying value | $ 265.0 | $ 350.0 |
| Variable Interest Entity, Not Primary Beneficiary | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Investments, present value of estimated future cash flows | 120.00% |