Commitments and Contingencies (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Loan commitments to extend credit	$ 7,697,724,000	$ 8,183,158,000
Standby letters of credit	368,979,000	355,503,000
Commitments to contribute capital to small business investment companies and CRA-related loan pools	50,518,000	40,698,000
Commitments to contribute capital to low income housing project partnerships	0	88,515,000
Commitments to contribute capital to private equity funds	50,000	50,000
Total	8,117,271,000	$ 8,667,924,000
Increase of investment in low income housing project partnerships	$ 101,000,000