Investments (Summary of Gross Unrealized Loss Position) (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
$ 291,131
|
$ 158,413
|
| Unrealized Losses 12 months or less |
(5,269)
|
(2,225)
|
| Fair Value Longer than 12 months |
28,890
|
27,548
|
| Unrealized Losses Longer than 12 months |
(5,604)
|
(1,752)
|
| Fair Value Total |
320,021
|
185,961
|
| Unrealized Losses Total |
(10,873)
|
(3,977)
|
| Debt Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
284,547
|
158,284
|
| Unrealized Losses 12 months or less |
(4,431)
|
(2,223)
|
| Fair Value Longer than 12 months |
28,890
|
27,548
|
| Unrealized Losses Longer than 12 months |
(5,604)
|
(1,752)
|
| Fair Value Total |
313,437
|
185,832
|
| Unrealized Losses Total |
(10,035)
|
(3,975)
|
| Equity Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
6,584
|
129
|
| Unrealized Losses 12 months or less |
(838)
|
(2)
|
| Fair Value Total |
6,584
|
129
|
| Unrealized Losses Total |
(838)
|
(2)
|
| U.S. Treasury securities and obligations of U.S. Government [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
41,428
|
15,005
|
| Unrealized Losses 12 months or less |
(61)
|
(4)
|
| Fair Value Total |
41,428
|
15,005
|
| Unrealized Losses Total |
(61)
|
(4)
|
| Corporate Bonds [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
96,475
|
7,552
|
| Unrealized Losses 12 months or less |
(1,822)
|
(85)
|
| Fair Value Total |
96,475
|
7,552
|
| Unrealized Losses Total |
(1,822)
|
(85)
|
| Collateralized Corporate Bank Loans [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
65,868
|
64,712
|
| Unrealized Losses 12 months or less |
(1,758)
|
(824)
|
| Fair Value Longer than 12 months |
3,532
|
8,898
|
| Unrealized Losses Longer than 12 months |
(124)
|
(1,091)
|
| Fair Value Total |
69,400
|
73,610
|
| Unrealized Losses Total |
(1,882)
|
(1,915)
|
| Municipal Bonds [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
44,525
|
50,546
|
| Unrealized Losses 12 months or less |
(488)
|
(945)
|
| Fair Value Longer than 12 months |
25,310
|
15,684
|
| Unrealized Losses Longer than 12 months |
(5,478)
|
(656)
|
| Fair Value Total |
69,835
|
66,230
|
| Unrealized Losses Total |
(5,966)
|
(1,601)
|
| Collateralized Mortgage Backed Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Fair Value 12 months or less |
36,251
|
20,469
|
| Unrealized Losses 12 months or less |
(302)
|
(365)
|
| Fair Value Longer than 12 months |
48
|
2,966
|
| Unrealized Losses Longer than 12 months |
(2)
|
(5)
|
| Fair Value Total |
36,299
|
23,435
|
| Unrealized Losses Total |
$ (304)
|
$ (370)
|