Capital Stock (Details 3) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted stock units
Antidilutive securities
Number of securities not included in computation of diluted earnings per share (in shares)	714	0	0
Stock Appreciation Rights (SARs)
Antidilutive securities
Number of securities not included in computation of diluted earnings per share (in shares)	2,474	491	306
Performance Shares [Member]
Antidilutive securities
Number of securities not included in computation of diluted earnings per share (in shares)	887	124	0