Securities (Securities Available for Sale with Unrealized Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	$ 1,063,994	$ 842,011
Available for sale, Losses less than 12 months, Gross Unrealized Losses	25,125	6,319
Available for sale, Losses 12 months or longer, Fair Value	1,710,404	1,569,320
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	87,749	39,099
Available for sale, Total, Fair Value	2,774,398	2,411,331
Available for sale, Total, Gross Unrealized Losses	112,874	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	42,423	45,616
Available for sale, Losses less than 12 months, Gross Unrealized Losses	1,812	42
Available for sale, Losses 12 months or longer, Fair Value	48,562	51,157
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	2,672	2,221
Available for sale, Total, Fair Value	90,985	96,773
Available for sale, Total, Gross Unrealized Losses	4,484	2,263
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	54,121	2,768
Available for sale, Losses less than 12 months, Gross Unrealized Losses	984	11
Available for sale, Losses 12 months or longer, Fair Value	168,133	173,530
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	7,536	3,335
Available for sale, Total, Fair Value	222,254	176,298
Available for sale, Total, Gross Unrealized Losses	8,520	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	559,924	461,835
Available for sale, Losses less than 12 months, Gross Unrealized Losses	8,483	4,195
Available for sale, Losses 12 months or longer, Fair Value	1,066,016	898,099
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	45,844	16,192
Available for sale, Total, Fair Value	1,625,940	1,359,934
Available for sale, Total, Gross Unrealized Losses	54,327	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	291,635	203,618
Available for sale, Losses less than 12 months, Gross Unrealized Losses	10,839	995
Available for sale, Losses 12 months or longer, Fair Value	396,809	411,046
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	30,551	16,868
Available for sale, Total, Fair Value	688,444	614,664
Available for sale, Total, Gross Unrealized Losses	41,390	17,863
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale, Losses less than 12 months, Fair Value	115,891	128,174
Available for sale, Losses less than 12 months, Gross Unrealized Losses	3,007	1,076
Available for sale, Losses 12 months or longer, Fair Value	30,884	35,488
Available for sale, Losses 12 months or longer, Gross Unrealized Losses	1,146	483
Available for sale, Total, Fair Value	146,775	163,662
Available for sale, Total, Gross Unrealized Losses	$ 4,153	$ 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
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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=82897076&loc=d3e27337-111563

Reference 2: 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

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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 less than twelve months.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ 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=82897076&loc=d3e27337-111563

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

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ References

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)(1)
-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
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: