Stock Repurchase Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2003
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock	$ 247,000
Stock repurchased, average price per share (in dollars per share)	$ 139.78
Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Authorized common stock for repurchases, amount				$ 15,000,000
Remaining authorized share for repurchases, amount	$ 250,000,000
Repurchase of common stock	$ 200,000
Number of shares repurchased	1,769	0	0