Stock-based Compensation (Details Narrative) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock compensation plan, total intrinsic values of options outstanding	$ 2,800,000
Total intrinsic value of exercisable options	$ 1,700,000
Discount percentage for post vesting restrictions	11.20%
Fair value restricted stock awards vested	$ 762,000	$ 994,000	$ 699,000
Weighted average grant date fair value	$ 130.35
Accrued dividend equivalents	$ 2,496,000
Stock-based compensation expense, total tax benefit recognized	444,000	765,000	441,000
Total fair value of stock units that vested	250,000
Stock-based compensation expense	1,731,000	1,682,000	1,659,000
General And Administrative Expense [Member]
Stock-based compensation expense	1,731,000	1,682,000	1,659,000
Directors [Member]
Total fair value of stock units that vested	$ 11,000	7,000	6,000
2006 Equity Incentive Plan
Weighted average grant date fair value	$ 646.90
Number of common shares reserved for future issuance	200,000
Granted shares of restricted stock	3,865
2006 Equity Incentive Plan | Restricted Stock [Member]
Terms of award	the restrictions usually lapse over a five-year period
Non Employee Directors [Member]
Value of stock units held for the accounts	$ 2,324,000
Non Employee Directors [Member] | 2006 Plan [Member]
Total value of stock awards		$ 240,000	$ 240,000