CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Restricted Stock	Restricted Stock Common Stock	Restricted Stock Additional Paid-in Capital	Stock Option	Stock Option Common Stock	Stock Option Additional Paid-in Capital
Beginning balance (in shares) at Dec. 31, 2016		36,199,704
Beginning balance at Dec. 31, 2016	$ 115,568	$ 362	$ 64,303	$ (20,000)	$ 70,903	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock (in shares)		16,968
Release of restricted stock, net	0
Common stock subject to possible redemption (in shares)								(16,968)			(54,976)
Common stock subject to possible redemption							$ (326)		$ (326)	$ (1,388)	$ (1)	$ (1,387)
Stock options exercised (in shares)		54,976
Stock option exercised	1,388	$ 1	1,387
Stock options exercised via repayment of non-recourse notes (in shares)		93,332
Stock options exercised via repayment of non-recourse notes	2,275	$ 1	2,274
Share-based compensation - equity awards	$ 1,658		1,658
Share repurchases (in shares)	(93,332)	(93,332)
Share repurchases	$ (2,275)	$ (1)	1	(2,275)
Deemed dividend related to changes in fair value of common stock subject to possible redemption	(2,344)				(2,344)
Net income	62,247				62,247
Ending balance (in shares) at Dec. 31, 2017		36,199,704
Ending balance at Dec. 31, 2017	176,803	$ 362	67,910	(22,275)	130,806	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock (in shares)		25,136
Release of restricted stock, net	0
Common stock subject to possible redemption (in shares)								(25,136)
Common stock subject to possible redemption							$ (685)		$ (685)
Stock options exercised via repayment of non-recourse notes (in shares)		1,771,096
Stock options exercised via repayment of non-recourse notes	44,757	$ 18	44,739
Share-based compensation - equity awards	$ 1,692		1,692
Share repurchases (in shares)	(338,648)	(338,648)
Share repurchases	$ (7,958)	$ (3)	3	(7,958)
Common stock no longer subject to possible redemption due to extinguishment of Puts (in shares)		357,224
Common stock no longer subject to possible redemption due to extinguishment of Puts	9,098	$ 3	9,095
Fair value of vested stock options converted from liability to equity awards	2,875		2,875
Deemed dividend related to changes in fair value of common stock subject to possible redemption	640				640
Net income	71,438				71,438
Ending balance (in shares) at Dec. 31, 2018		37,989,376
Ending balance at Dec. 31, 2018	298,660	$ 380	125,629	(30,233)	202,884
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock (in shares)		226,817
Release of restricted stock, net	(426)	$ 2	(428)
Dividends and dividend equivalents - $0.20 per share	(7,596)				(7,596)
Share-based compensation - equity awards	3,826		3,826
Retirement of treasury shares	$ 0		(30,233)	30,233
Share repurchases (in shares)	(9,079,690)	(9,079,690)
Share repurchases	$ (223,075)			(223,075)
Stock issued for purchase of Dover Downs (in shares)		2,976,825
Stock issued for purchase of Dover Downs	86,780	$ 30	86,750
Other comprehensive loss	(1,888)					(1,888)
Net income	55,130				55,130
Ending balance (in shares) at Dec. 31, 2019		32,113,328
Ending balance at Dec. 31, 2019	$ 211,411	$ 412	$ 185,544	$ (223,075)	$ 250,418	$ (1,888)