Federal Funds Purchased and Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Federal Funds Purchased	$ 250,000	$ 30,000	$ 80,000
Securities Sold under Agreements to Repurchase	36,928	32,169	59,624
Federal Funds Purchased
Short-term Debt [Line Items]
Maximum outstanding at any month-end	250,000	100,000	180,000
Average balance for the year	$ 36,722	$ 22,742	$ 29,542
Weighted average rate at end of year	2.64%	1.50%	0.75%
Weighted average rate paid for the year	1.89%	1.19%	0.54%
Securities Sold Under Agreements to Repurchase
Short-term Debt [Line Items]
Maximum outstanding at any month-end	$ 85,257	$ 67,249	$ 77,466
Average balance for the year	$ 65,370	$ 58,872	$ 66,282
Weighted average rate at end of year	0.15%	0.09%	0.05%
Weighted average rate paid for the year	0.11%	0.09%	0.05%