Share-Based Compensation - Summary of Option Activity (Details) - Option Activity Under the 2003 Plan $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Shares
Outstanding, beginning of year (in shares) | shares	12,675
Granted (in shares) | shares	0
Exercised (in shares) | shares	(8,625)
Forfeited (in shares) | shares	0
Outstanding, end of year (in shares) | shares	4,050
Exercisable, end of year (in shares) | shares	4,050
Weighted– Average Exercise Price
Outstanding, beginning of year (in dollars per share) | $ / shares	$ 5.42
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	4.45
Forfeited (in dollars per share) | $ / shares	0
Outstanding, end of year (in dollars per share) | $ / shares	7.49
Exercisable, end of year (in dollars per share) | $ / shares	$ 7.49
Outstanding, Weighted Average Remaining Contractual Term	1 year 5 months 12 days
Exercisable, Weighted Average Remaining Contractual Term	1 year 5 months 12 days
Outstanding, Aggregate Intrinsic Value | $	$ 33,885
Exercisable, Aggregate Intrinsic Value | $	$ 33,885