Commitments, Contingencies and Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commitments to Extend Credit
Letters of credit	$ 1,860,414	$ 1,796,647
Other Commitments
Unfunded commitments for investments in AHP and other tax credit investments	193,809
Accrued Expenses and Other Liabilities
Commitments to Extend Credit
Allowance for unfunded credit commitments	11,100	12,400
Other Commitments
Unfunded commitments for investments in AHP and other tax credit investments	193,800	161,000
Standby Letters of Credit
Commitments to Extend Credit
Letters of credit	1,810,000
Commercial Letters Of Credit
Commitments to Extend Credit
Letters of credit	48,500
Loans sold or securitized with recourse | Single Family Residential and Multi-Family Residential | Loans Sold or Securitized with Recourse | Accrued Expenses and Other Liabilities
Commitments to Extend Credit
Allowance for unfunded credit commitments	$ 76	$ 123