Derivatives and Hedging Activities - Summary of Effect of Derivative Instruments on Income Statement (Detail) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Derivatives, Fair Value [Line Items] | ||
| Total gain (loss) on derivative financial instruments | $ 336 | $ 195 |
| Interest Rate Swaps [Member] | Other Income [Member] | ||
| Derivatives, Fair Value [Line Items] | ||
| Total gain (loss) on derivative financial instruments | (167) | $ 195 |
| Interest Rate Loan Commitments [Member] | Mortgage Banking Income [Member] | ||
| Derivatives, Fair Value [Line Items] | ||
| Total gain (loss) on derivative financial instruments | 98 | |
| Best Efforts Forward Delivery Commitments [Member] | Mortgage Banking Income [Member] | ||
| Derivatives, Fair Value [Line Items] | ||
| Total gain (loss) on derivative financial instruments | (5) | |
| Forward TBA Contracts [Member] | Mortgage Banking Income [Member] | ||
| Derivatives, Fair Value [Line Items] | ||
| Total gain (loss) on derivative financial instruments | $ 410 | |