Allowance for Loan Losses - Recorded Investment Segregated by Amounts Individually or Collectively in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	$ 1,433,201	$ 1,043,371
Balance, end of period: Individually evaluated for impairment	21,645	24,673
Balance, end of period: Collectively evaluated for impairment	1,411,556	1,018,698
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	768,988	411,327
Balance, end of period: Individually evaluated for impairment	11,443	16,077
Balance, end of period: Collectively evaluated for impairment	757,545	395,250
Real estate construction one-to-four family
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	38,148	38,503
Balance, end of period: Individually evaluated for impairment	702	1,349
Balance, end of period: Collectively evaluated for impairment	37,446	37,154
Real estate construction other
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	75,333	60,906
Balance, end of period: Individually evaluated for impairment	0	0
Balance, end of period: Collectively evaluated for impairment	75,333	60,906
Real estate term owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	153,942	138,181
Balance, end of period: Individually evaluated for impairment	6,794	5,104
Balance, end of period: Collectively evaluated for impairment	147,148	133,077
Real estate term non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	317,333	311,302
Balance, end of period: Individually evaluated for impairment	802	178
Balance, end of period: Collectively evaluated for impairment	316,531	311,124
Real estate term other
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	40,989	42,200
Balance, end of period: Individually evaluated for impairment	1,551	1,594
Balance, end of period: Collectively evaluated for impairment	39,438	40,606
Consumer secured by 1st deed of trust
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	14,496	16,191
Balance, end of period: Individually evaluated for impairment	268	281
Balance, end of period: Collectively evaluated for impairment	14,228	15,910
Consumer other
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance, end of period	23,972	24,761
Balance, end of period: Individually evaluated for impairment	85	90
Balance, end of period: Collectively evaluated for impairment	$ 23,887	$ 24,671