Borrowings - Stated Maturity and Maturity to Call Date (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Stated maturity, 2020	$ 3,216,459
Stated maturity, 2021	4,199,011
Stated maturity, 2022	3,403,692
Stated maturity, 2023	1,805,077
Stated maturity, 2024	1,028,583
Stated maturity, 2025 and after	1,781,295
Maturity to Call Date, 2020	3,216,459
Maturity to Call Date, 2021	4,199,011
Maturity to Call Date, 2022	3,403,692
Maturity to Call Date, 2023	1,805,077
Maturity to Call Date, 2024	1,028,583
Maturity to Call Date, 2025 and after	1,781,295
Total principal amount, maturity to call date	15,434,117
Hedge accounting adjustments	45,887
Total principal amount, after adjustments	15,480,004
Brokered Deposits
Debt Instrument [Line Items]
Stated maturity, 2020	2,650,654
Stated maturity, 2021	3,691,692
Stated maturity, 2022	2,690,974
Stated maturity, 2023	1,270,385
Stated maturity, 2024	499,112
Stated maturity, 2025 and after	92,822
Maturity to Call Date, 2020	2,650,654
Maturity to Call Date, 2021	3,691,692
Maturity to Call Date, 2022	2,690,974
Maturity to Call Date, 2023	1,270,385
Maturity to Call Date, 2024	499,112
Maturity to Call Date, 2025 and after	92,822
Total principal amount, maturity to call date	10,895,639
Hedge accounting adjustments	45,887
Total principal amount, after adjustments	10,941,526
Unsecured Debt
Debt Instrument [Line Items]
Stated maturity, 2020	0
Stated maturity, 2021	0
Stated maturity, 2022	200,000
Stated maturity, 2023	0
Stated maturity, 2024	0
Stated maturity, 2025 and after	0
Maturity to Call Date, 2020	0
Maturity to Call Date, 2021	0
Maturity to Call Date, 2022	200,000
Maturity to Call Date, 2023	0
Maturity to Call Date, 2024	0
Maturity to Call Date, 2025 and after	0
Total principal amount, maturity to call date	200,000
Hedge accounting adjustments	0
Total principal amount, after adjustments	200,000
Secured Borrowings
Debt Instrument [Line Items]
Stated maturity, 2020	565,805
Stated maturity, 2021	507,319
Stated maturity, 2022	512,718
Stated maturity, 2023	534,692
Stated maturity, 2024	529,471
Stated maturity, 2025 and after	1,688,473
Maturity to Call Date, 2020	565,805
Maturity to Call Date, 2021	507,319
Maturity to Call Date, 2022	512,718
Maturity to Call Date, 2023	534,692
Maturity to Call Date, 2024	529,471
Maturity to Call Date, 2025 and after	1,688,473
Total principal amount, maturity to call date	4,338,478
Hedge accounting adjustments	0
Total principal amount, after adjustments	$ 4,338,478

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
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