Convertible Subordinated Notes (Details) - USD ($)
shares in Thousands |
3 Months Ended |
6 Months Ended |
|
|
|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
May 07, 2018 |
Dec. 31, 2017 |
Mar. 19, 2014 |
| Debt Instrument [Line Items] |
|
|
|
|
|
|
|
| Effect of dilutive securities, Convertible junior subordinated debentures (in shares) |
117
|
1,064
|
674
|
1,077
|
|
|
|
| Carrying Values of Liability and Equity Components, Convertible Subordinated Notes |
|
|
|
|
|
|
|
| Debt issuance costs |
$ 0
|
|
$ 0
|
|
|
$ (967,000)
|
|
| Accumulated Amortization, Debt Issuance Costs |
4,518,000
|
|
4,518,000
|
|
|
4,442,000
|
|
| Carrying value of the liability component |
$ 318,807,000
|
|
318,807,000
|
|
|
0
|
|
| Contractual coupon interest expense |
|
|
1,900,000
|
|
|
|
|
| Amortization of Debt Issuance Costs |
|
|
$ 320,000
|
$ 408,000
|
|
|
|
| Convertible Subordinated Notes [Member] |
|
|
|
|
|
|
|
| Debt Instrument [Line Items] |
|
|
|
|
|
|
|
| Stated interest rate percentage |
2.75%
|
|
2.75%
|
|
|
|
2.75%
|
| Carrying Values of Liability and Equity Components, Convertible Subordinated Notes |
|
|
|
|
|
|
|
| Convertible subordinated notes, principal amount |
$ 28,764,000
|
|
$ 28,764,000
|
|
$ 115,000,000
|
143,750,000
|
$ 143,750,000
|
| Unamortized discount of liability component |
(3,042,000)
|
|
(3,042,000)
|
|
|
(17,559,000)
|
|
| Debt issuance costs |
(297,000)
|
|
(297,000)
|
|
|
(1,750,000)
|
|
| Accumulated Amortization, Debt Issuance Costs |
1,746,000
|
|
1,746,000
|
|
|
1,359,000
|
|
| Carrying value of the liability component |
25,425,000
|
|
25,425,000
|
|
|
124,441,000
|
|
| Equity component carrying value |
3,585,000
|
|
3,585,000
|
|
|
$ 17,973,000
|
|
| Convertible subordinated notes, fair value |
34,300,000
|
|
34,300,000
|
|
|
|
|
| Contractual coupon interest expense |
500,000
|
$ 1,000,000
|
1,500,000
|
2,000,000
|
|
|
|
| Accretion of discount, convertible subordinated notes |
$ 600,000
|
$ 1,100,000
|
$ 1,700,000
|
$ 2,100,000
|
|
|
|
| Effective interest rate percentage |
3.15%
|
11.36%
|
3.15%
|
11.36%
|
|
|
|
| Amortization of Debt Issuance Costs |
$ 100,000
|
$ 100,000
|
$ 200,000
|
$ 300,000
|
|
|
|