Investment Securities - Securities Available for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	$ 3,649,979	$ 3,688,091
Gross Unrealized Gains	213,336	112,651
Gross Unrealized Losses	(12,174)	(3,555)
Securities available-for-sale	3,851,141	3,797,187
Government agency and government-sponsored enterprise pass through securities
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	1,060,551	1,083,182
Gross Unrealized Gains	72,587	25,579
Gross Unrealized Losses	(52)	(537)
Securities available-for-sale	1,133,086	1,108,224
Government agency and government-sponsored enterprise collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	993,696	1,112,573
Gross Unrealized Gains	56,055	24,403
Gross Unrealized Losses	(9)	(579)
Securities available-for-sale	1,049,742	1,136,397
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	825,446	691,647
Gross Unrealized Gains	62,976	43,851
Gross Unrealized Losses	(84)	(339)
Securities available-for-sale	888,338	735,159
Agency residential MBS
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	236,134	294,606
Gross Unrealized Gains	12,847	10,593
Gross Unrealized Losses	(47)	(1)
Securities available-for-sale	248,934	305,198
Asset-backed Securities
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	232,081	216,133
Gross Unrealized Gains	556	320
Gross Unrealized Losses	(5,431)	(1,670)
Securities available-for-sale	227,206	214,783
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	142,080	124,134
Gross Unrealized Gains	0	25
Gross Unrealized Losses	(5,417)	(403)
Securities available-for-sale	136,663	123,756
Private label collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	95,629	96,066
Gross Unrealized Gains	2,245	3,430
Gross Unrealized Losses	(1,099)	(13)
Securities available-for-sale	96,775	99,483
SBA asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	42,375	47,765
Gross Unrealized Gains	2,236	506
Gross Unrealized Losses	(35)	(13)
Securities available-for-sale	44,576	48,258
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	17,000	17,000
Gross Unrealized Gains	3,458	3,748
Gross Unrealized Losses	0	0
Securities available-for-sale	20,458	20,748
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Total securities available-for-sale	4,987	4,985
Gross Unrealized Gains	376	196
Gross Unrealized Losses	0	0
Securities available-for-sale	$ 5,363	$ 5,181

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

No definition available.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

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- Definition

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+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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