Securities (Securities Available for Sale with Unrealized Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Losses less than 12 months, Fair Value	$ 2,085,962	$ 1,857,312
Available for Sale, Losses less than 12 months, Gross Unrealized Losses	41,321	56,218
Available for Sale, Losses 12 months or longer, Fair Value	2,539	3,738
Available for Sale, Losses 12 months or longer, Gross Unrealized Losses	65	69
Available for Sale, Total, Fair Value	2,088,501	1,861,050
Available for Sale, Total, Gross Unrealized Losses	41,386	56,287
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	74,308	54,788
Available for Sale, Losses less than 12 months, Gross Unrealized Losses	1,306	1,923
Available for Sale, Total, Fair Value	74,308	54,788
Available for Sale, Total, Gross Unrealized Losses	1,306	1,923
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Losses less than 12 months, Fair Value	213,557	228,588
Available for Sale, Losses less than 12 months, Gross Unrealized Losses	5,941	11,186
Available for Sale, Total, Fair Value	213,557	228,588
Available for Sale, Total, Gross Unrealized Losses	5,941	11,186
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Losses less than 12 months, Fair Value	1,315,878	1,087,644
Available for Sale, Losses less than 12 months, Gross Unrealized Losses	16,245	19,359
Available for Sale, Losses 12 months or longer, Fair Value	2,539	3,738
Available for Sale, Losses 12 months or longer, Gross Unrealized Losses	65	69
Available for Sale, Total, Fair Value	1,318,417	1,091,382
Available for Sale, Total, Gross Unrealized Losses	16,310	19,428
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Losses less than 12 months, Fair Value	407,937	402,591
Available for Sale, Losses less than 12 months, Gross Unrealized Losses	17,277	23,159
Available for Sale, Total, Fair Value	407,937	402,591
Available for Sale, Total, Gross Unrealized Losses	17,277	23,159
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Losses less than 12 months, Fair Value	74,282	83,701
Available for Sale, Losses less than 12 months, Gross Unrealized Losses	552	591
Available for Sale, Total, Fair Value	74,282	83,701
Available for Sale, Total, Gross Unrealized Losses	$ 552	$ 591

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=73527792&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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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
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563

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