Fair Value of Financial Instruments - Hierarchy Table on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Level 1
Fair Value Disclosures
Collateral dependent loans/Impaired loans	$ 0	$ 0
Level 2
Fair Value Disclosures
Collateral dependent loans/Impaired loans	0	0
Level 3
Fair Value Disclosures
Collateral dependent loans/Impaired loans	13,276,121	13,351,092
Nonrecurring
Fair Value Disclosures
Collateral dependent loans/Impaired loans	606	4,077
Nonrecurring | Level 1
Fair Value Disclosures
Collateral dependent loans/Impaired loans	0	0
Nonrecurring | Level 2
Fair Value Disclosures
Collateral dependent loans/Impaired loans	0	0
Nonrecurring | Level 3
Fair Value Disclosures
Collateral dependent loans/Impaired loans	$ 606	$ 4,077