Shareholders' Equity, Common Stock Dividends and Treasury Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock Dividends [Abstract]
Dividend declared (in dollars per share)	$ 0.25	$ 0.25	$ 0.25
Dividends paid (in dollars per share)	$ 0.25	$ 0.25	$ 0.25
Treasury Stock [Abstract]
Purchases of Loews treasury stock (in shares)	22.0	21.5	20.3
Purchases of Loews treasury stock	$ 917	$ 1,059	$ 1,011
Treasury stock retired (in shares)	22.0