Stock-Based Compensation Employee share purchase plan (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Defined Contribution Plan Disclosure [Line Items] | ||
| Employee Stock Ownership Plan (ESOP), Compensation Expense | $ 0.2 | $ 0.1 |
| Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate | 5.00% | |
| Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay | 100.00% | |