Investments in Qualified Affordable Housing Partnerships, Tax Credit and Other Investments, Net and Variable Interest Entities (Investments in Tax Credit and Other Investments, Net) (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) credit	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Investments in Tax Credit and Other Investments, Net [Line Items]
Investments in tax credit and other investments, net	$ 268,330,000		$ 254,140,000
Accrued expenses and other liabilities — Unfunded commitments	121,604,000		113,515,000
Amortization expense of tax credit and other investments	17,325,000	$ 24,905,000
Unrealized gains recognized on marketable equity securities held	38,000	392,000
Equity securities without readily determinable fair values	19,100,000		19,100,000
Adjustments to equity securities without readily determinable fair values	0	0
Tax Credit Investments, Pre-tax Impairment Recovery	$ 150,000	0
Number of recovered historic tax credit investments | credit	1
AFS debt securities	$ 3,695,943,000		3,317,214,000
Collateralized loan obligations (“CLOs”)
Investments in Tax Credit and Other Investments, Net [Line Items]
AFS debt securities	259,878,000		284,706,000
Tax credit investments
Investments in Tax Credit and Other Investments, Net [Line Items]
Marketable equity securities	30,300,000		$ 31,700,000
Amortization of tax credit and other investments
Investments in Tax Credit and Other Investments, Net [Line Items]
No OTTI charge	$ 0
DC Solar Tax Credit Investments | Amortization of tax credit and other investments
Investments in Tax Credit and Other Investments, Net [Line Items]
No OTTI charge		$ 7,000,000.0