Investment Securities - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) security	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) security	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Summary of Investment Holdings [Line Items]
Allowance for credit losses for available-for-sale debt securities	$ 0		$ 0		$ 0
Accrued interest receivable	$ 25,600,000		$ 25,600,000		27,000,000
Number of securities in security portfolio | security	1,925		1,925
Number of securities in unrealized loss position | security	329		329
Total investment securities - available-for-sale	$ 7,027,950,000		$ 7,027,950,000		5,970,115,000
Unrealized losses	73,677,000		73,677,000		11,385,000
Equity securities, at fair value	12,427,000		12,427,000		2,547,000
Gains on equity securities	100,000	$ 500,000	300,000	$ 1,300,000
Impairments on equity securities without readily determinable fair value			0	0
Other Assets
Summary of Investment Holdings [Line Items]
Equity securities without readily determinable fair value	$ 124,800,000		$ 124,800,000		105,800,000
Pooled trust preferred securities
Summary of Investment Holdings [Line Items]
Number of pooled trust preferred securities | security	2		2
Total investment securities - available-for-sale	$ 9,367,000		$ 9,367,000		7,913,000
Unrealized losses	$ 4,384,000		4,384,000		$ 5,850,000
Other-than-temporary impairment loss			$ 0	$ 0