Securities Available-for-Sale - Amortized Cost and Fair Value of Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
$ 649,198
|
$ 650,782
|
| Fair Value |
671,128
|
660,963
|
| Obligations of the U.S. Treasury, U.S. government corporations and agencies, and obligations of states and political subdivisions |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Due in one year or less, Amortized Cost |
52,302
|
|
| Due after one year through five years, Amortized Cost |
216,729
|
|
| Due after five years through ten years, Amortized Cost |
55,893
|
|
| Due after ten years, Amortized Cost |
60,508
|
|
| Available-for-sale Securities, Debt Maturities, Amortized Cost |
385,432
|
|
| Due in one year or less, Fair Value |
52,439
|
|
| Due after one year through five years, Fair Value |
222,114
|
|
| Due after five years through ten years, Fair Value |
58,699
|
|
| Due after ten years, Fair Value |
65,264
|
|
| Fair Value, Debt securities |
398,516
|
|
| Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
134,675
|
128,458
|
| Fair Value |
137,460
|
128,835
|
| Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
34,685
|
39,185
|
| Fair Value |
36,285
|
40,125
|
| Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
86,827
|
69,697
|
| Fair Value |
88,499
|
69,204
|
| Debt Securities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
641,619
|
643,203
|
| Fair Value |
660,760
|
651,294
|
| Marketable Equity Securities |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Amortized Cost |
7,579
|
7,579
|
| Fair Value |
$ 10,368
|
$ 9,669
|