Stock-Based Compensation - Aggregate Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-based compensation additional disclosures
Tax benefit recognized from stock options exercised	$ 5,000	$ 11,600	$ 1,500
Total stock-based compensation expense	13,376	9,261	7,680
Stock Options
Stock-based compensation additional disclosures
Total stock-based compensation expense	7,307	4,550	3,183
Performance Stock Options
Stock-based compensation additional disclosures
Total stock-based compensation expense	0	0	1,534
Restricted stock units
Stock-based compensation additional disclosures
Total stock-based compensation expense	3,719	3,052	2,273
Performance Stock Units
Stock-based compensation additional disclosures
Total stock-based compensation expense	867	589	0
Employee stock purchase plan
Stock-based compensation additional disclosures
Total stock-based compensation expense	$ 1,483	$ 1,070	$ 690