Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Held-to-maturity Securities	$ 2,827,769	$ 1,819,901
Threshold Net Book Balance, Individually Evaluated Loans	1,000
Interest Receivable	80,600	70,600
Liability Recorded for Expected Credit Losses on Unfunded Commitments	30,400
Other Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued interest receivable for investment securities	25,400	19,200
Interest Receivable	80,600	70,600
Other Liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liability Recorded for Expected Credit Losses on Unfunded Commitments	$ 30,400	$ 30,500