Summary of Significant Accounting Policies - Weighted Average Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share Basic And Diluted Other Disclosures [Abstract]
Weighted average shares outstanding - basic	44,979	46,114	45,313	45,997
Dilutive effect of equity incentive plan instruments	1,758		1,751	1,922
Weighted average shares outstanding - diluted	46,737	46,114	47,064	47,919