Statements of Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid	$ 36,211	$ 17,277
Interest expense paid on deposits and borrowings	35,246	64,881
Noncash transfers from loans to other real estate	496	5,684
Finance right-of-use assets resulting from lease liabilities		9,823
Operating right-of-use assets resulting from lease liabilities	2,368	$ 33,180
Transfer of long-term FHLB advances to short-term	$ 651