Securities (Amortized Cost and Fair Value of Securities Available for Sale) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	$ 4,637,610	$ 2,755,806
Securities Available for Sale, Gross Unrealized Gains	52,367	7,500
Securities Available for Sale, Gross Unrealized Losses	14,673	72,269
Securities Available for Sale, Fair Value	4,675,304	2,691,037
U.S. Treasury And Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	98,320	74,339
Securities Available for Sale, Gross Unrealized Gains	652
Securities Available for Sale, Gross Unrealized Losses	300	2,633
Securities Available for Sale, Fair Value	98,672	71,706
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	242,016	246,713
Securities Available for Sale, Gross Unrealized Gains	7,789	360
Securities Available for Sale, Gross Unrealized Losses		6,646
Securities Available for Sale, Fair Value	249,805	240,427
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	1,910,909	1,468,912
Securities Available for Sale, Gross Unrealized Gains	20,268	4,284
Securities Available for Sale, Gross Unrealized Losses	7,020	29,794
Securities Available for Sale, Fair Value	1,924,157	1,443,402
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	1,570,765	799,060
Securities Available for Sale, Gross Unrealized Gains	19,880	1,953
Securities Available for Sale, Gross Unrealized Losses	4,178	30,936
Securities Available for Sale, Fair Value	1,586,467	770,077
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	807,600	163,282
Securities Available for Sale, Gross Unrealized Gains	3,757	903
Securities Available for Sale, Gross Unrealized Losses	3,142	2,260
Securities Available for Sale, Fair Value	808,215	161,925
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	8,000	3,500
Securities Available for Sale, Gross Unrealized Gains	21
Securities Available for Sale, Gross Unrealized Losses	33
Securities Available for Sale, Fair Value	$ 7,988	$ 3,500

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

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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- Definition

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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