Fair Value (Details) - USD ($)
$ in Thousands |
12 Months Ended |
|
Dec. 31, 2016 |
Jun. 30, 2017 |
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
$ 1,429,538
|
$ 1,424,871
|
| Obligations of U.S. Government sponsored entities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
527,627
|
528,380
|
| Obligations of U.S. states and political subdivisions |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
89,056
|
92,445
|
| U.S. Government agencies |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
158,226
|
148,482
|
| U.S. Government sponsored entities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
651,430
|
652,387
|
| Non-U.S. Government agencies or sponsored entities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
116
|
96
|
| U.S. corporate debt securities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
2,162
|
2,162
|
| Equity securities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
921
|
919
|
| Recurring | Obligations of U.S. Government sponsored entities | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Obligations of U.S. Government sponsored entities | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
527,627
|
528,380
|
| Recurring | Obligations of U.S. Government sponsored entities | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Obligations of U.S. states and political subdivisions | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Obligations of U.S. states and political subdivisions | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
89,056
|
92,445
|
| Recurring | Obligations of U.S. states and political subdivisions | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | U.S. Government agencies | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | U.S. Government agencies | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
158,226
|
148,482
|
| Recurring | U.S. Government agencies | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | U.S. Government sponsored entities | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | U.S. Government sponsored entities | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
651,430
|
652,387
|
| Recurring | U.S. Government sponsored entities | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Non-U.S. Government agencies or sponsored entities | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Non-U.S. Government agencies or sponsored entities | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
116
|
96
|
| Recurring | Non-U.S. Government agencies or sponsored entities | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | U.S. corporate debt securities | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | U.S. corporate debt securities | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
2,162
|
2,162
|
| Recurring | U.S. corporate debt securities | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Equity securities | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Equity securities | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
0
|
0
|
| Recurring | Equity securities | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
921
|
919
|
| Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) |
0
|
|
| Recurring | Fair Value | Obligations of U.S. Government sponsored entities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
527,627
|
528,380
|
| Recurring | Fair Value | Obligations of U.S. states and political subdivisions |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
89,056
|
92,445
|
| Recurring | Fair Value | U.S. Government agencies |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
158,226
|
148,482
|
| Recurring | Fair Value | U.S. Government sponsored entities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
651,430
|
652,387
|
| Recurring | Fair Value | Non-U.S. Government agencies or sponsored entities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
116
|
96
|
| Recurring | Fair Value | U.S. corporate debt securities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
2,162
|
2,162
|
| Recurring | Fair Value | Equity securities |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Available-for-sale securities, at fair value |
$ 921
|
$ 919
|