Short-Term Borrowings and Long-Term Debt Repurchase Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Amount outstanding as of December 31	$ 883,241	$ 754,777	$ 617,524
Customer repurchase agreements
Short-term Debt [Line Items]
Amount outstanding as of December 31	$ 56,707	$ 43,500	$ 172,017
Weighted average interest rate as of December 31	0.69%	0.25%	0.13%
Average amount outstanding during the year	$ 58,383	$ 138,198	$ 188,974
Weighted average interest rate during the year	0.67%	0.21%	0.12%