Long-term Debt - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
Jan. 31, 2018	Dec. 31, 2019
Senior debentures \| 2022 senior debentures
Debt Instrument [Line Items]
Earliest redemption date		Aug. 14, 2020
Redemption price (percent)		100.00%
Maturity date		Feb. 14, 2022
Senior debentures \| 2027 senior debentures
Debt Instrument [Line Items]
Earliest redemption date		Aug. 14, 2025
Redemption price (percent)		100.00%
Maturity date		Feb. 14, 2027
Subordinated debentures \| 2025 subordinated debentures
Debt Instrument [Line Items]
Maturity date		Nov. 30, 2025
Earliest date allowed for prepayment		Nov. 30, 2020
Aggregate principal amount		$ 11,500,000
Subordinated debentures \| 2028 subordinated debentures
Debt Instrument [Line Items]
Maturity date	Jan. 30, 2028
Aggregate principal amount	$ 100,000,000

Earliest date when the debt instrument can be prepaid, in CCYY-MM-DD format.

No definition available.

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- Definition

Earliest date before maturity when the issuer can call the outstanding debt instrument for repayment or conversion to equity, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 942
-SubTopic 470
-Section 50
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-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Balance Type:	credit
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- 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.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
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-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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- Details

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