Subsequent Events (Details)		12 Months Ended
	Feb. 02, 2021 USD ($) $ / shares shares	Jan. 04, 2021 USD ($)	Dec. 31, 2020 $ / shares shares	Dec. 31, 2019 $ / shares shares
Subsequent Event [Line Items]
Preferred stock, shares issued | shares			350,000	350,000
Preferred stock, par value | $ / shares			$ 0.001	$ 0.001
Subsequent Event | Global fund banking
Subsequent Event [Line Items]
Potential credit exposure related to loan transaction under investigation | $	$ 70,000,000
Subsequent Event | Senior Notes | 1.800% Senior Notes
Subsequent Event [Line Items]
Principal value | $	$ 500,000,000
Stated interest rate	1.80%
Subsequent Event | Series B Preferred Stock
Subsequent Event [Line Items]
Preferred stock, depositary share ownership interest	1.00%
Preferred stock, shares issued | shares	750,000
Preferred stock, par value | $ / shares	$ 0.001
Preferred stock, liquidation preference (usd per share) | $ / shares	100,000
Preferred stock, liquidation preference per depositary share (usd per share) | $ / shares	$ 1,000
Preferred stock, dividend rate (percent)	4.10%
Preferred stock, period interval for subsequent rate calculations	10 years
Preferred stock, dividend rate, percentage margin	3.064%
Subsequent Event | Boston Private Financial Holdings, Inc.
Subsequent Event [Line Items]
Total consideration | $		$ 900,000,000
Cash issued per acquiree share | $		$ 2.10
Entity shares issued per acquiree share		0.0228