Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets:
Deferred compensation expense	$ 56,148	$ 56,989
Allowance for loan and lease losses and nonperforming assets	35,195	38,245
Lease liabilities	11,951
Investment securities	2,474	45,846
State income taxes	3,338	5,378
Total deferred income tax assets before valuation allowance	109,106	146,458
Valuation allowance	(1,393)	(1,901)
Total deferred income tax assets after valuation allowance	107,713	144,557
Liabilities:
Leases	(14,873)	(10,597)
Deferred income	(16,069)	(15,471)
Lease right-of-use assets	(11,931)
Intangible assets	(500)	(788)
Other	(10,570)	(9,852)
Total deferred income tax liabilities	(53,943)	(36,708)
Net deferred income tax assets	$ 53,770	$ 107,849