Common Stock Issued and Outstanding - Activity in the Number of Common Stock Issued and Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year (in shares)	152,935,361	173,058,829	172,572,873
Stock options exercised (in shares)	11,359	12,345	21,200
Restricted stock awards (in shares)	651,905	561,729	464,756
Treasury shares purchased (in shares)	0	(20,697,542)	0
End of year (in shares)	153,598,625	152,935,361	173,058,829