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Shareholders' Equity and Other Comprehensive Income (Narrative) (Details) |  |  |  |  | 12 Months Ended |  |  |  |  |  |
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Jul. 01, 2019 USD ($) $ / shares | Jan. 01, 2019 USD ($) shares | Aug. 01, 2018 USD ($) $ / shares shares | Jun. 21, 2018 USD ($) $ / shares | Dec. 31, 2020 USD ($) shares | Dec. 31, 2019 USD ($) shares | Dec. 31, 2018 USD ($) shares | Oct. 31, 2020 USD ($) shares | Nov. 30, 2019 USD ($) shares | Jun. 17, 2019 USD ($) | Jun. 16, 2019 USD ($) | Jan. 15, 2019 USD ($) | Nov. 30, 2018 USD ($) shares
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of stock |  |  |  |  |  | $ 0 | $ 342,005,000 | $ 65,140,000 |  |  |  |  |  |
Cash dividends paid | [1] |  |  |  |  | 33,163,000 | 22,881,000 | 13,978,000 |  |  |  |  |  |
Repurchases of common stock |  |  |  |  |  | $ 16,246,000 | $ 725,398,000 | 175,072,000 |  |  |  |  |  |
Repurchase of common stock (in shares) | shares |  |  |  |  |  | 450,000 | 19,903,000 |  |  |  |  |  |  |
Stock repurchase program, authorized amount |  |  |  |  |  |  |  | 150,000,000.0 |  |  | $ 725,000,000.0 | $ 325,000,000.0 | $ 400,000,000.0 |
Warrant outstanding (in shares) | shares |  |  | 913,000 |  |  |  |  |  |  |  |  |  |  |
Warrants exercised and common stock reissued (in shares) | shares |  |  |  |  |  |  | 263,000 |  |  |  |  |  |  |
Common stock |  |  |  |  |  | $ 168,133,000 | $ 166,801,000 |  |  |  |  |  |  |
Common stock, shares issued (in shares) | shares |  |  |  |  |  | 168,132,522 | 166,800,623 |  |  |  |  |  |  |
Fourth Quarter of 2017 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock repurchase program, authorized amount |  |  |  |  |  |  |  | 25,000,000.0 |  |  |  |  |  |
Series E Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of stock |  | $ 350,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Payments of stock issuance costs |  | $ 342,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Redemption period from regulatory capital treatment |  | 90 days |  |  |  |  |  |  |  |  |  |  |  |
Redemption price per share (in dollars per share) | $ / shares |  | $ 25 |  |  |  |  |  |  |  |  |  |  |  |
Series E Preferred Stock | Until July 1, 2024 (Excluding July 1, 2024) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend rate, percentage |  | 587.50% |  |  |  |  |  |  |  |  |  |  |  |
Series E Preferred Stock | From July 1, 2024 (Including July 1, 2024) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend rate, percentage |  | 4.127% |  |  |  |  |  |  |  |  |  |  |  |
Series D Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of stock |  |  |  |  | $ 200,000,000.0 |  |  |  |  |  |  |  |  |
Payments of stock issuance costs |  |  |  |  | $ 195,100,000 |  |  |  |  |  |  |  |  |
Redemption period from regulatory capital treatment |  |  |  |  | 90 days |  |  |  |  |  |  |  |  |
Redemption price per share (in dollars per share) | $ / shares |  |  |  |  | $ 25 |  |  |  |  |  |  |  |  |
Liquidation preference (in dollars per share) | $ / shares |  |  |  |  | $ 25 |  |  |  |  |  |  |  |  |
Series D Preferred Stock | From and Excluding June 21, 2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend rate, percentage |  |  |  |  | 6.30% |  |  |  |  |  |  |  |  |
Series D Preferred Stock | From and Including June 21, 2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend rate, percentage |  |  |  |  | 3.352% |  |  |  |  |  |  |  |  |
Series C Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Redemption price per share (in dollars per share) | $ / shares |  |  |  | $ 25 |  |  |  |  |  |  |  |  |  |
Cash dividends paid |  |  |  | $ 2,600,000 |  |  |  |  |  |  |  |  |  |
Repurchases of common stock |  |  |  |  |  |  |  | 130,000,000 |  |  |  |  |  |
FCB Financial Holdings, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued in acquisitions (in shares) | shares |  |  | 49,500,000 |  |  |  |  |  |  |  |  |  |  |
Consideration transferred |  |  | $ 1,630,000,000 |  |  |  |  |  |  |  |  |  |  |
FCB Financial Holdings, Inc. | FCB Financial Holdings, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Merger exchange ratio |  |  | 1.055 |  |  |  |  |  |  |  |  |  |  |
Global One |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock |  |  |  |  |  |  |  |  | $ 8,700,000 | $ 11,800,000 |  |  |  | $ 7,400,000
Common stock, shares issued (in shares) | shares |  |  |  |  |  |  |  |  | 379,000 | 344,000 |  |  |  | 199,000
Preferred Stock | Series C Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock redeemed or called during period (in shares) | shares |  |  |  | 5,200,000 |  |  |  |  |  |  |  |  |  |
Stock redeemed or called during period |  |  |  | $ 130,000,000.0 |  |  |  |  |  |  |  |  |  |
Dividends declared on preferred stock during the year but paid after year-end |  |  |  | $ 4,000,000.0 |  |  |  |  |  |  |  |  |  |
Repurchases of common stock |  |  |  |  |  |  |  | $ 125,980,000 |  |  |  |  |  |
Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued in acquisitions (in shares) | shares |  |  |  |  |  | 379,000 | 344,000 | 199,000 |  |  |  |  |  |
Repurchases of common stock |  |  |  |  |  |  | $ 725,000,000.0 | $ 175,000,000.0 |  |  |  |  |  |
Repurchase of common stock (in shares) | shares |  |  |  |  |  | 450,000 | 19,900,000 | 3,700,000 |  |  |  |  |  |
Warrants exercised and common stock reissued (in shares) | shares |  |  |  |  |  |  | 260,000 |  |  |  |  |  |  |
Common Stock | FCB Financial Holdings, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued in acquisitions (in shares) | shares |  |  |  |  |  |  | 22,043,000 |  |  |  |  |  |  |
Treasury Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchases of common stock |  |  |  |  |  | $ 16,246,000 | $ 725,398,000 | $ 175,072,000 |  |  |  |  |  |
Repurchase of common stock (in shares) | shares |  |  |  |  |  |  |  | 3,653,000 |  |  |  |  |  |
Warrants exercised and common stock reissued (in shares) | shares |  |  |  |  |  |  | (260,000) |  |  |  |  |  |  |
[1] | For the year ended December 31, 2020, dividends per share were $1.58 and $1.47 for Series D and Series E Preferred Stock, respectively. For the year ended December 31, 2019, dividends per share were $1.58 and $0.73 for Series D and Series E Preferred Stock, respectively. For the year ended December 31, 2018, dividends per share were $1.48 and $0.79 for Series C and D Preferred Stock. respectively. (2) For additional information, see "Part II - Item 8. Financial Statements and Supplementary Data - Note 1 - Summary of Significant Accounting Policies.

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