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Equity (Details) |  |  |  |  |  | 3 Months Ended | 12 Months Ended | 48 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 12, 2019 USD ($) | May 13, 2019 USD ($) $ / shares shares | Jun. 20, 2014 $ / shares shares | Mar. 25, 2014 | Jan. 17, 2013 $ / shares shares | Dec. 31, 2019 USD ($) $ / shares shares | Sep. 30, 2019 USD ($) $ / shares | Jun. 30, 2019 USD ($) $ / shares | Mar. 31, 2019 USD ($) $ / shares | Dec. 31, 2018 USD ($) $ / shares shares | Sep. 30, 2018 $ / shares | Jun. 30, 2018 $ / shares | Mar. 31, 2018 $ / shares | Dec. 31, 2017 $ / shares | Sep. 30, 2017 $ / shares | Jun. 30, 2017 $ / shares | Mar. 31, 2017 $ / shares | Dec. 31, 2019 USD ($) security director $ / shares shares | Dec. 31, 2018 USD ($) security $ / shares shares | Dec. 31, 2017 USD ($) security $ / shares shares | Dec. 31, 2019 USD ($) shares | Mar. 14, 2019 USD ($) | Sep. 30, 2015 USD ($)
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Quarterly dividend on all classes of common stock (in dollars per share) | $ / shares |  |  |  |  |  | $ 0.70 | $ 0.70 | $ 0.70 | $ 0.70 | $ 0.58 | $ 0.58 | $ 0.58 | $ 0.58 | $ 0.36 | $ 0.36 | $ 0.36 | $ 0.36 |  |  |  |  |  |
Repurchase of stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 75,000,000 | $ 0 | $ 0 |  |  |
Deferred issuance costs |  |  |  |  |  | $ 0 | $ 0 | $ 1,956,000 | $ 0 |  |  |  |  |  |  |  |  | $ 1,956,000 | $ 0 | $ 0 |  |  |
Expiration period of SARs (in years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |  |  |
Exercise price of SARs granted (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 82.76 | $ 86.15 | $ 60.84 |  |  |
Tax benefit from exercise of stock options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000.0 | $ 1,500,000 | $ 2,600,000 |  |  |
Excess tax benefits related to stock-based awards |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 449,000 | 946,000 | 860,000 |  |  |
Net decrease to additional paid-in capital related to stock-based compensation awards |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (1,800,000) | (2,700,000) | (2,600,000) |  |  |
Number of board of directors electing to receive shares | director |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 |  |  |  |  |
SARs outstanding (in shares) | shares |  |  |  |  |  | 98,836 |  |  |  |  |  |  |  |  |  |  |  | 98,836 |  |  | 98,836 |  |
Intrinsic value of options, SARs, and non-vested restricted stock outstanding, exercisable, and vested or expected to vest |  |  |  |  |  | $ 8,900,000 |  |  |  | $ 7,900,000 |  |  |  |  |  |  |  | $ 8,900,000 | 7,900,000 |  | $ 8,900,000 |  |
Total intrinsic value of options and SARs exercised |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,900,000 | $ 3,000,000.0 | $ 3,800,000 |  |  |
Total unrecognized compensation cost related to non-vested SARs and restricted stock awards |  |  |  |  |  | 2,700,000 |  |  |  |  |  |  |  |  |  |  |  | $ 2,700,000 |  |  | 2,700,000 |  |
Compensation cost recognition period (in years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 year 9 months 18 days |  |  |  |  |
Weighted-average grant date fair values of options, SARs, and restricted stock awards granted (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 58.27 | $ 69.38 | $ 44.93 |  |  |
Compensation expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,300,000 | $ 2,500,000 | $ 2,700,000 |  |  |
Weighted-average grant date fair value of the restricted stock awarded (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 80.51 | $ 84.03 | $ 59.79 |  |  |
Capital required for capital adequacy |  |  |  |  |  | 618,800,000 |  |  |  | 545,000,000.0 |  |  |  |  |  |  |  | $ 618,800,000 | $ 545,000,000.0 |  | 618,800,000 |  |
Capital |  |  |  |  |  | 815,400,000 |  |  |  | 727,600,000 |  |  |  |  |  |  |  | 815,400,000 | 727,600,000 |  | 815,400,000 |  |
Excess capital |  |  |  |  |  | $ 196,600,000 |  |  |  | $ 182,600,000 |  |  |  |  |  |  |  | $ 196,600,000 | $ 182,600,000 |  | $ 196,600,000 |  |
Employee Stock Option |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
SARs outstanding (in shares) | shares |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  | 0 |  |
Restricted Stock | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Vesting period of awards |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 year |  |  |  |  |
Restricted Stock | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Vesting period of awards |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |
5.700% Non-Cumulative Preferred Stock, Series D |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  | 4,000,000 |  |  |  | 4,000,000 |  |  |  | 4,000,000 |  |  |  |  |  |  |  | 4,000,000 | 4,000,000 |  | 4,000,000 |  |
Dividend rate (as a percent) |  | 5.70% |  | 6.875% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidation value (in dollars per share) | $ / shares |  | $ 25.00 |  |  | $ 25.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate outstanding |  | $ 100,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of stock | $ 75,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,300,000 |  |  |  |  |
Dividends on preferred stock (in dollars per share) | $ / shares |  |  |  |  |  | $ 0.35625 | $ 0.35625 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Series B Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  |  |  | 3,000,000 |  |  |  | 3,000,000 |  |  |  |  |  |  |  | 3,000,000 | 3,000,000 |  | 3,000,000 |  |
Deferred issuance costs | $ 2,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,900,000 |  |  |  |  |
Dividends on preferred stock (in dollars per share) | $ / shares |  |  |  |  |  |  |  | $ 0.4297 | $ 0.4297 | $ 0.4297 | 0.4297 | 0.4297 | 0.4297 | 0.4297 | 0.4297 | 0.4297 | 0.4297 |  |  |  |  |  |
Series B Preferred Stock | Second Quarter 2019 Not Including April 17, 2019 to and including June 12, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends on preferred stock (in dollars per share) | $ / shares |  |  |  |  |  |  |  | 0.2626 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class C non-voting common stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock authorized for repurchase |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 10,000,000.0 | $ 25,000,000.0
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 668,000 |  |  |  |  |
Shares repurchased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 19,600,000 |  |
Class C shares issued (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 768 | 174 | 698 |  |  |
Fair value of Class C stock issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 60,000 | $ 14,000 | $ 41,000 |  |  |
Number of board of directors electing to receive shares | security |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 | 4 | 4 |  |  |
5.875% Non-Cumulative Preferred Stock, Series A |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  |  | 2,400,000 | 2,400,000 |  |  |  | 2,400,000 |  |  |  |  |  |  |  | 2,400,000 | 2,400,000 |  | 2,400,000 |  |
Dividend rate (as a percent) |  |  |  |  | 5.875% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidation value (in dollars per share) | $ / shares |  |  |  |  | $ 25.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,700,000 |  |  |  |  |
Dividends on preferred stock (in dollars per share) | $ / shares |  |  |  |  |  | $ 0.3672 | 0.3672 | 0.3672 | 0.3672 | $ 0.3672 | 0.3672 | 0.3672 | 0.3672 | 0.3672 | 0.3672 | 0.3672 | 0.3672 |  |  |  |  |  |
6.000% Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series C |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  | 3,000,000 |  |  | 3,000,000 |  |  |  | 3,000,000 |  |  |  |  |  |  |  | 3,000,000 | 3,000,000 |  | 3,000,000 |  |
Dividend rate (as a percent) |  |  | 6.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidation value (in dollars per share) | $ / shares |  |  | $ 25.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,600,000 |  |  |  |  |
Dividends on preferred stock (in dollars per share) | $ / shares |  |  |  |  |  | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 | $ 0.3750 |  |  |  |  |  |
6.000% Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series C | July 17, 2024, thereafter |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend variable rate (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.26% |  |  |  |  |

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- Definition The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share. + 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 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(d)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(d)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644 + Details
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- Definition Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt. + References Reference 1: 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Value of all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by shareholders, which is net of related treasury stock. May be all or a portion of the number of preferred shares authorized. These shares represent the ownership interest of the preferred shareholders. + References Reference 1: 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Number of shares of stock issued attributable to transactions classified as other. + References No definition available. + Details
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- Definition Amount of stock repurchase plan authorized. + References No definition available. + Details
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