Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands		Total		Cumulative effect of change in accounting principle	Common Stock	Additional paid-in capital	Retaining earnings	Retaining earnings Cumulative effect of change in accounting principle	Accumulated other comprehensive income	Accumulated other comprehensive income Cumulative effect of change in accounting principle
Balance, beginning of year (in shares) at Dec. 31, 2017					24,916,806
Balance, beginning of year at Dec. 31, 2017		$ 973,373		$ 0	$ 25	$ 196,334	$ 608,700	$ 191,244	$ 168,314	$ (191,244)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		27,650					27,650
Shares repurchased (in shares)					(120,372)
Shares repurchased		(5,404)				(5,404)
Stock based compensation (in shares)					300,974
Stock based compensation		7,171				7,171
Dividends on common stock		(105,408)					(105,408)
Change in net unrealized investment appreciation	[1]	(32,944)							(32,944)
Net unrealized investment depreciation of discontinued operations, sold		(6,714)					(6,714)
Change in liability for underfunded employee benefit plans	[2]	25,402							25,402
Compensation expense and related tax benefit for stock-based award grants		5,249				5,249
Balance, ending of year (in shares) at Dec. 31, 2018					25,097,408
Balance, end of year at Dec. 31, 2018		888,375		(514)	$ 25	203,350	715,472	(514)	(30,472)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		14,820					14,820
Shares repurchased (in shares)					(258,756)
Shares repurchased		(11,700)				(11,700)
Stock based compensation (in shares)					177,311
Stock based compensation		2,377				2,377
Dividends on common stock		(32,662)					(32,662)
Change in net unrealized investment appreciation	[1]	56,602							56,602
Change in liability for underfunded employee benefit plans	[2]	(12,978)							(12,978)
Compensation expense and related tax benefit for stock-based award grants		$ 6,152				6,152
Balance, ending of year (in shares) at Dec. 31, 2019		25,015,963			25,015,963
Balance, end of year at Dec. 31, 2019		$ 910,472		$ (30)	$ 25	200,179	697,116	$ (30)	13,152
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(112,706)					(112,706)
Shares repurchased (in shares)					(70,467)
Shares repurchased		(2,741)				(2,741)
Stock based compensation (in shares)					109,983
Stock based compensation		(71)				(71)
Dividends on common stock		(28,526)					(28,526)
Change in net unrealized investment appreciation		35,791	[1]						35,791
Change in liability for underfunded employee benefit plans		17,968	[2]						17,968
Compensation expense and related tax benefit for stock-based award grants		$ 4,992				4,992
Balance, ending of year (in shares) at Dec. 31, 2020		25,055,479			25,055,479
Balance, end of year at Dec. 31, 2020		$ 825,149			$ 25	$ 202,359	$ 555,854		$ 66,911

[1] The change in net unrealized appreciation is net of reclassification adjustments and income taxes.

[2] The change in liability for underfunded employee benefit plans is net of income taxes.