Loans Receivable and Allowance for Credit Losses (Loan Purchases, Sales and Transfers) (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	$ 81,166,000	$ 129,864,000	$ 173,394,000	$ 285,631,000
Sales	78,776,000	178,916,000	173,519,000	293,203,000
Purchases	178,471,000	309,776,000	326,285,000	389,822,000
Write-down of loans transferred from loans held-for-investment to loans held-for-sale recorded to allowance for loan losses	317,000	13,300,000	390,000	13,400,000
Net gains from sales of loans held-for-sale during the period, excluding lower of cost or fair value adjustment	15,000	2,300,000	930,000	3,900,000
Loans held-for-sale
Loans Receivable and Allowance for Credit Losses
Lower of cost or fair value adjustment	0	0	0	0
Commercial and industrial (“C&I”) \| Originated
Loans Receivable and Allowance for Credit Losses
Sales	55,700,000		132,200,000
Commercial and industrial and commercial real estate \| Originated
Loans Receivable and Allowance for Credit Losses
Sales		103,500,000		193,200,000
Loans sold in secondary market \| Purchased
Loans Receivable and Allowance for Credit Losses
Sales	23,100,000	75,400,000	41,300,000	100,000,000.0
Commercial lending \| Commercial and industrial (“C&I”)
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	79,593,000	99,449,000	155,166,000	245,840,000
Sales	76,031,000	140,326,000	151,677,000	242,691,000
Purchases	159,100,000	285,615,000	266,294,000	350,362,000
Commercial lending \| Commercial real estate (“CRE”)
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	0	30,415,000	16,655,000	39,791,000
Sales	0	30,415,000	16,655,000	39,791,000
Purchases	0	0	0	0
Commercial lending \| Real estate loan \| Multifamily residential
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	0	0	0	0
Sales	0	0	0	0
Purchases	1,734,000	3,249,000	5,952,000	3,435,000
Commercial lending \| Construction and land
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	1,573,000	0	1,573,000	0
Sales	1,573,000	0	1,573,000	0
Purchases	0	0	0	0
Consumer lending \| Real estate loan \| Single-family residential
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	0	0	0	0
Sales	1,172,000	8,175,000	3,614,000	10,721,000
Purchases	$ 17,637,000	$ 20,912,000	$ 54,039,000	$ 36,025,000

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties.

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Amount of increase from purchase of financing receivable.

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Amount of decrease from sale and reclassification to held-for-sale of financing receivable.

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The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans and leases that were sold during the reporting period. This element refers to the gain (loss) and not to the cash proceeds of the sales. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.

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