Stockholders' Deficit (Summary of Common Stock Repurchase) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2025	Jun. 30, 2024
Equity [Abstract]
Treasury Stock Shares Repurchased	0.6	1.6
Treasury Stock Shares Repurchased for Tax Withholding and Other	0.0	0.1
Common stock repurchase, share	0.6	1.7
Aggregate cost of share	$ 162.6	$ 392.6
Treasury stock, value, repurchased for tax withholding	4.2	15.9
Payments for Repurchase of Common Stock	$ 166.8	$ 408.5	$ 660.2
Treasury stock shares repurchased, average cost per share	$ 264.71	$ 240.46
Total repurchases for tax withholdings and other, average cost per share	280.71	240.77
Average stock price	$ 265.09	$ 240.47