Organization and Summary of Significant Accounting Policies - Accounting Standards Adopted (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Allowance for Credit Losses - Loans and Leases	$ 208,454	$ 130,530	$ 141,718	$ 137,253
Liabilities
Cumulative-Effect Adjustment of a Change in Accounting Principle, Net of Tax	437,072
Benefit (provision) for income taxes	(57,970)	(97,306)	$ (93,784)
Cumulative-Effect Adjustment of a Change in Accounting Principle, Net of Tax	473,974	437,072
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment
Assets
Allowance for Credit Losses - Loans and Leases		770
Liabilities
Cumulative-Effect Adjustment of a Change in Accounting Principle, Net of Tax	17,070
Benefit (provision) for income taxes		(4,553)
Cumulative-Effect Adjustment of a Change in Accounting Principle, Net of Tax		17,070
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Included in other liabilities
Liabilities
Reserve for Unfunded Commitments		16,300
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect, adjusted balance
Assets
Allowance for Credit Losses - Loans and Leases		131,300
Liabilities
Cumulative-Effect Adjustment of a Change in Accounting Principle, Net of Tax	$ (12,517)
Cumulative-Effect Adjustment of a Change in Accounting Principle, Net of Tax		(12,517)
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect, adjusted balance | Included in other liabilities
Liabilities
Reserve for Unfunded Commitments		16,900
Prior to Adoption | ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments
Assets
Allowance for Credit Losses - Loans and Leases		130,530
Prior to Adoption | ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Included in other liabilities
Liabilities
Reserve for Unfunded Commitments		$ 600