Consolidated Balance Sheets (Parenthetical) - shares	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, shares outstanding	110,781,613	94,461,576	93,622,934	96,380,102
Common stock, shares issued	122,061,711	121,662,540
Treasury stock, shares	11,280,098	27,200,964