Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Class C Special Stock [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Class C Special Stock [Member]	Additional Paid-in Capital [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss, Net of Tax [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Loss, Net of Tax [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Total
Balance at Dec. 31, 2018	$ 0	$ 1	$ 0	$ 0	$ 0	$ 186,812	$ 0	$ (659)	$ 0	$ (379)	$ 2	$ 11,488	$ 2	$ 197,263
Balance (in shares) at Dec. 31, 2018		11,863						11
Stock-based Compensation Expense		$ 0		0		6,773		$ 0		0		0		6,773
Treasury stock purchases for restricted stock vests		0		0		0		$ (1,031)		0		0		(1,031)
Treasury stock purchases for restricted stock vests (in shares)								17
Issuance of Common Shares upon Stock Option and ESPP Exercise		$ 0		0		4,852		$ 0		0		0		4,852
Issuance of Common Shares upon Stock Option and ESPP Exercise (in shares)		120						(16)
Issuance of Restricted Stock Awards		$ 0		0		(967)		$ 967		0		0		0
Issuance of Restricted Stock Awards (in shares)		106
Change in Fair Value of Interest Rate Swap, Net of Tax		$ 0		0		0		0		(5,658)		0		(5,658)
Net income/(loss)		0		0		0		0		0		10,929		10,929
Balance at Sep. 30, 2019		$ 1		0		197,470		$ (723)		(6,037)		22,419		213,130
Balance (in shares) at Sep. 30, 2019		12,089						12
Balance at Jun. 30, 2019		$ 1				194,867		$ (723)		(5,013)		18,524		207,656
Balance (in shares) at Jun. 30, 2019		12,086						12
Stock-based Compensation Expense						2,470								2,470
Issuance of Common Shares upon Stock Option and ESPP Exercise						133								133
Issuance of Common Shares upon Stock Option and ESPP Exercise (in shares)		3
Change in Fair Value of Interest Rate Swap, Net of Tax										(1,024)				(1,024)
Net income/(loss)												3,895		3,895
Balance at Sep. 30, 2019		$ 1		0		197,470		$ (723)		(6,037)		22,419		213,130
Balance (in shares) at Sep. 30, 2019		12,089						12
Balance at Dec. 31, 2019	$ 0	$ 1	$ 0	0	$ 0	200,800	$ 0	$ (723)	$ 0	(4,871)	$ (8)	17,584	$ (8)	212,791
Balance (in shares) at Dec. 31, 2019		12,105						15
Stock-based Compensation Expense		$ 0		0		10,543		$ 0		0		0		10,543
Treasury stock purchases for restricted stock vests		0		0		0		$ (1,523)		0		0		(1,523)
Treasury stock purchases for restricted stock vests (in shares)								61
Issuance of Common Shares upon Stock Option and ESPP Exercise		$ 0		0		449		$ 0		0		0		449
Issuance of Common Shares upon Stock Option and ESPP Exercise (in shares)		14
Issuance of Restricted Stock Awards		$ 0		0		0		0		0		0		0
Issuance of Restricted Stock Awards (in shares)		304
Change in Fair Value of Interest Rate Swap, Net of Tax		$ 0		0		0		0		(8,239)		0		(8,239)
Net income/(loss)		0		0		0		0		0		(18,913)		(18,913)
Balance at Sep. 30, 2020		$ 1		0		211,792		$ (2,246)		(13,110)		(1,337)		195,100
Balance (in shares) at Sep. 30, 2020		12,423						76
Balance at Jun. 30, 2020		$ 1				209,409		$ (2,246)		(14,049)		(1,771)		191,344
Balance (in shares) at Jun. 30, 2020		12,380						58
Stock-based Compensation Expense						2,383								2,383
Treasury stock purchases for restricted stock vests (in shares)								18
Issuance of Restricted Stock Awards (in shares)		43
Change in Fair Value of Interest Rate Swap, Net of Tax										939				939
Net income/(loss)												434		434
Balance at Sep. 30, 2020		$ 1		$ 0		$ 211,792		$ (2,246)		$ (13,110)		$ (1,337)		$ 195,100
Balance (in shares) at Sep. 30, 2020		12,423						76