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CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]      
Cash dividends declared per share (in dollars per share) $ 3.60 $ 3.04 $ 2.8
Reclassification adjustment of stranded taxes on available-for-sale investments resulting from U.S. tax law changes enacted on December 22, 2017     $ 1.7