Loans and the Allowance for Credit Losses - Summary of Commercial Loans by Risk Grade (Detail) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
$ 6,276,204
|
$ 6,296,157
|
| Commercial Portfolio Segment [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
4,133,559
|
4,119,775
|
| Commercial Portfolio Segment [Member] | Pass [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
4,065,208
|
4,045,825
|
| Commercial Portfolio Segment [Member] | Criticized [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
33,785
|
36,092
|
| Commercial Portfolio Segment [Member] | Classified - Substandard [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
34,566
|
37,858
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
440,896
|
392,597
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Pass [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
434,665
|
386,753
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Criticized [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
3,384
|
2,984
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Classified - Substandard [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
2,847
|
2,860
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
2,574,330
|
2,601,851
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Pass [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
2,526,334
|
2,548,805
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Criticized [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
24,807
|
25,673
|
| Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Classified - Substandard [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
23,189
|
27,373
|
| Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
1,118,333
|
1,125,327
|
| Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Pass [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
1,104,209
|
1,110,267
|
| Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Criticized [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
5,594
|
7,435
|
| Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Classified - Substandard [Member] |
|
|
| Summary of commercial loans by risk grade |
|
|
| Commercial loans |
$ 8,530
|
$ 7,625
|