Securities (Amortized Cost and Fair Value of Securities Held to Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	$ 2,500,220	$ 2,370,388
Securities Held to Maturity, Gross Unrealized Gains	7,896	21,304
Securities Held to Maturity, Gross Unrealized Losses	37,999	15,841
Securities Held to Maturity, Fair Value	2,470,117	2,375,851
U.S. Treasury And Government Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	50,000	50,000
Securities Held to Maturity, Gross Unrealized Losses	44	410
Securities Held to Maturity, Fair Value	49,956	49,590
Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	648,093	185,890
Securities Held to Maturity, Gross Unrealized Gains	2,147	3,475
Securities Held to Maturity, Gross Unrealized Losses	20,175	1,166
Securities Held to Maturity, Fair Value	630,065	188,199
Residential Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	862,162	1,014,135
Securities Held to Maturity, Gross Unrealized Gains	4,329	15,585
Securities Held to Maturity, Gross Unrealized Losses	3,068	1,589
Securities Held to Maturity, Fair Value	863,423	1,028,131
Commercial Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	75,739
Securities Held to Maturity, Gross Unrealized Losses	4,038
Securities Held to Maturity, Fair Value	71,701
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	864,226	1,120,363
Securities Held to Maturity, Gross Unrealized Gains	1,420	2,244
Securities Held to Maturity, Gross Unrealized Losses	10,674	12,676
Securities Held to Maturity, Fair Value	$ 854,972	$ 1,109,931

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.6)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

+ References

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity.

+ References

+ Details

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

- Definition

Fair value of investments in debt securities classified as held-to-maturity.

+ References

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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