Securities (Amortized Cost and Fair Value of Securities Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	$ 3,480,949	$ 2,755,806
Securities Available for Sale, Gross Unrealized Gains	71,914	7,500
Securities Available for Sale, Gross Unrealized Losses	3,206	72,269
Securities Available for Sale, Fair Value	3,549,657	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	93,415	74,339
Securities Available for Sale, Gross Unrealized Gains	1,726
Securities Available for Sale, Gross Unrealized Losses		2,633
Securities Available for Sale, Fair Value	95,141	71,706
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	243,941	246,713
Securities Available for Sale, Gross Unrealized Gains	8,222	360
Securities Available for Sale, Gross Unrealized Losses		6,646
Securities Available for Sale, Fair Value	252,163	240,427
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	1,321,109	1,468,912
Securities Available for Sale, Gross Unrealized Gains	20,598	4,284
Securities Available for Sale, Gross Unrealized Losses	2,236	29,794
Securities Available for Sale, Fair Value	1,339,471	1,443,402
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	1,585,956	799,060
Securities Available for Sale, Gross Unrealized Gains	39,066	1,953
Securities Available for Sale, Gross Unrealized Losses	853	30,936
Securities Available for Sale, Fair Value	1,624,169	770,077
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	232,577	163,282
Securities Available for Sale, Gross Unrealized Gains	2,302	903
Securities Available for Sale, Gross Unrealized Losses	63	2,260
Securities Available for Sale, Fair Value	234,816	161,925
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Gross Amortized Cost	3,951	3,500
Securities Available for Sale, Gross Unrealized Losses	54
Securities Available for Sale, Fair Value	$ 3,897	$ 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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