Loans and the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Receivables [Abstract]
Non Accrual Contractual Due	90 days
Loans Pledged as Collateral	$ 2,500,000		$ 2,300,000
Loans performing under the restructured terms	8,200		11,200
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	22,700		23,300
Troubled debt restructurings	30,900		$ 34,500
Specific allowance	$ 0	$ 147

Loans performing under the restructured terms

No definition available.

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- Definition

Non accrual contractual due.

+ References

No definition available.

+ Details

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- Definition

Specific allowance.

+ References

No definition available.

+ Details

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- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18794-111554

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- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5086-111524

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- References

No definition available.

+ Details

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- Definition

For a debtor, the gain (loss) recognized on the transfer of assets, after the impact of income tax expense or benefit, arising from the difference between the book value of the assets transferred before the restructuring and the fair value of the assets transferred.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 60
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6402221&loc=d3e15743-112638

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