Accounting Standards Updates and Recently Adopted Standards (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in ACL		$ 88,375	$ 65,547	$ 64,783	$ 64,613
Increase in ACL for loans		81,905	62,089	61,642	61,203
Increase in ACL for unfunded commitments		6,470	3,458	3,141	3,410
Reduction in equity		(1,640,612)	(1,635,692)	(1,508,158)	(1,457,554)
Adoption of CECL
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in ACL			8,751
Increase in ACL for loans			6,880
Increase in ACL for unfunded commitments			1,871
Reduction in equity			3,529		549
Adoption of CECL | ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in ACL			8,750
Increase in ACL for loans			6,880
Increase in ACL for unfunded commitments			1,870
Increase reclassified from amortized cost basis of PCD financial assets previously classified as PCI	$ 3,590
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in equity		$ (54,206)	(40,152)	$ 59,573	90,419
Retained earnings | Adoption of CECL
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in equity			$ 3,529		$ 549
Retained earnings | Adoption of CECL | ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in equity	$ 3,530