Goodwill and Other Intangible Assets - Summary of Core Deposit Intangibles, Customer Renewal Lists and Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
---|---|---|
Finite-Lived Intangible Assets [Line Items] | ||
Gross carrying amount | $ 172,152 | $ 136,711 |
Accumulated amortization | (104,825) | (91,067) |
Net carrying amount | 67,327 | 45,644 |
Core Deposit Intangibles [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross carrying amount | 139,886 | 111,594 |
Accumulated amortization | (89,888) | (79,362) |
Net carrying amount | 49,998 | 32,232 |
Customer Renewal Lists [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross carrying amount | 12,352 | 12,351 |
Accumulated amortization | (8,544) | (7,860) |
Net carrying amount | 3,808 | 4,491 |
Mortgage Servicing Rights [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross carrying amount | 19,914 | 12,766 |
Accumulated amortization | (6,393) | (3,845) |
Net carrying amount | $ 13,521 | $ 8,921 |