Fair Value Measurements (Narrative) (Details) - USD ($) |
Mar. 31, 2019 |
Mar. 19, 2014 |
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Liabilities measured at fair value | $ 0 | |
| Convertible Subordinated Notes [Member] | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Stated interest rate percentage | 2.75% | 2.75% |
| Long-term debt measured at fair value | $ 6,800,000 | |
| Senior Notes [Member] | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Stated interest rate percentage | 6.625% | |
| Long-term debt measured at fair value | $ 332,400,000 |