Stock-Based Compensation - Weighted-Average Assumptions Used to Determine Fair Value of SARs Grants on Date of Grant Using Black-Scholes-Merton Valuation Model (Details) - Stock appreciation rights	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Expected stock price volatility	23.00%	21.00%	21.00%
Risk-free interest rate	1.50%	2.50%	2.50%
Expected life	4 years 8 months 4 days	4 years 7 months 2 days	4 years 6 months 7 days