Shareholders' Equity and Earnings Per Common Share, Earings Per Share Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share Reconciliation [Abstract]
Net income		$ 22,037	$ 4,810
Weighted average shares outstanding (in shares)	[1]	21,826,000	22,271,000
Stock units for deferred compensation plan for non-employee directors (in shares)		120,000	122,000
Effect of stock options (in shares)		83,000	99,000
Performance share units (in shares)		30,000	37,000
Weighted average shares outstanding for calculation of diluted earnings per share (in shares)		22,059,000	22,529,000
Net income per common share [Abstract]
Basic (in dollars per share)	[1]	$ 1.01	$ 0.22
Diluted (in dollars per share)		$ 1.00	$ 0.21
Stock Options [Member]
Antidilutive Securities [Abstract]
Antidilutive shares excluded from computation of diluted loss per share (in shares)		0	0

[1] Basic net income per common share includes weighted average common shares outstanding during the period and participating share awards.