Securities (Details) - USD ($)
$ in Thousands |
Jun. 30, 2017 |
Dec. 31, 2016 |
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
$ 1,433,013
|
$ 1,442,724
|
| Gross Unrealized Gains |
6,137
|
6,233
|
| Gross Unrealized Losses |
14,279
|
19,419
|
| Fair Value |
1,424,871
|
1,429,538
|
| Obligations of U.S. Government sponsored entities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
526,734
|
527,057
|
| Gross Unrealized Gains |
2,906
|
2,873
|
| Gross Unrealized Losses |
1,260
|
2,303
|
| Fair Value |
528,380
|
527,627
|
| Obligations of U.S. states and political subdivisions |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
92,151
|
89,910
|
| Gross Unrealized Gains |
593
|
286
|
| Gross Unrealized Losses |
299
|
1,140
|
| Fair Value |
92,445
|
89,056
|
| U.S. Government agencies |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
149,281
|
159,417
|
| Gross Unrealized Gains |
1,025
|
1,081
|
| Gross Unrealized Losses |
1,824
|
2,272
|
| Fair Value |
148,482
|
158,226
|
| U.S. Government sponsored entities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
661,251
|
662,724
|
| Gross Unrealized Gains |
1,613
|
1,993
|
| Gross Unrealized Losses |
10,477
|
13,287
|
| Fair Value |
652,387
|
651,430
|
| Non-U.S. Government agencies or sponsored entities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
96
|
116
|
| Gross Unrealized Gains |
0
|
0
|
| Gross Unrealized Losses |
0
|
0
|
| Fair Value |
96
|
116
|
| U.S. corporate debt securities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
2,500
|
2,500
|
| Gross Unrealized Gains |
0
|
0
|
| Gross Unrealized Losses |
338
|
338
|
| Fair Value |
2,162
|
2,162
|
| Total debt securities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
1,432,013
|
1,441,724
|
| Gross Unrealized Gains |
6,137
|
6,233
|
| Gross Unrealized Losses |
14,198
|
19,340
|
| Fair Value |
1,423,952
|
1,428,617
|
| Equity securities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
1,000
|
1,000
|
| Gross Unrealized Gains |
0
|
0
|
| Gross Unrealized Losses |
81
|
79
|
| Fair Value |
$ 919
|
$ 921
|