Securities (Securities Available for Sale with Unrealized Losses) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	$ 442,773	$ 842,011
Available for sale, Losses less than 12 months, Gross Unrealized Losses	4,928	6,319
Available for sale, Losses 12 months or longer, Fair Value	1,687,704	1,569,320
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	67,340	39,099
Available for sale, Total, Fair Value	2,130,477	2,411,331
Available for sale, Total, Gross Unrealized Losses	72,268	45,418
U.S. Treasury And Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value		45,616
Available for sale, Losses less than 12 months, Gross Unrealized Losses		42
Available for sale, Losses 12 months or longer, Fair Value	71,706	51,157
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	2,633	2,221
Available for sale, Total, Fair Value	71,706	96,773
Available for sale, Total, Gross Unrealized Losses	2,633	2,263
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	41,203	2,768
Available for sale, Losses less than 12 months, Gross Unrealized Losses	591	11
Available for sale, Losses 12 months or longer, Fair Value	170,883	173,530
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	6,054	3,335
Available for sale, Total, Fair Value	212,086	176,298
Available for sale, Total, Gross Unrealized Losses	6,645	3,346
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	305,090	461,835
Available for sale, Losses less than 12 months, Gross Unrealized Losses	2,485	4,195
Available for sale, Losses 12 months or longer, Fair Value	762,826	898,099
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	27,309	16,192
Available for sale, Total, Fair Value	1,067,916	1,359,934
Available for sale, Total, Gross Unrealized Losses	29,794	20,387
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	96,226	203,618
Available for sale, Losses less than 12 months, Gross Unrealized Losses	1,851	995
Available for sale, Losses 12 months or longer, Fair Value	570,485	411,046
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	29,085	16,868
Available for sale, Total, Fair Value	666,711	614,664
Available for sale, Total, Gross Unrealized Losses	30,936	17,863
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	254	128,174
Available for sale, Losses less than 12 months, Gross Unrealized Losses	1	1,076
Available for sale, Losses 12 months or longer, Fair Value	111,804	35,488
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	2,259	483
Available for sale, Total, Fair Value	112,058	163,662
Available for sale, Total, Gross Unrealized Losses	$ 2,260	$ 1,559

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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