Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Components of income tax expense
Current	$ 10,128	$ 6,552
Deferred	17,047	15,447
Total income tax expense	27,175	21,999
Effective Income Tax Rate Reconciliation, Amount
Tax provision at weighted average statutory rates	27,376	23,938
Non-deductible expenses	714	324
Excess tax benefits from stock-based compensation	(620)	(1,956)
Tax exempt interest, net of proration	(342)	(443)
Other	47	136
Total income tax expense	$ 27,175	$ 21,999
% of pretax income
Tax provision at weighted average statutory rates	15.50%	16.00%
Non-deductible expenses	0.40%	0.20%
Excess tax benefits from stock-based compensation	(0.30%)	(1.30%)
Tax exempt interest, net of proration	(0.20%)	(0.30%)
Other	0.00%	0.10%
Total income tax expense	15.40%	14.70%