Stockholders' Equity (Narrative) (Details) € in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 EUR (€) shares	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)	Nov. 27, 2019 shares	Dec. 11, 2018 USD ($)	Apr. 25, 2017 USD ($)
Stockholders' Equity Note [Abstract]
Dividends	$ 232,800,000	$ 238,100,000	€ 238.1	$ 60,600,000	€ 60.6
Payments for Repurchase of Common Stock	92,700,000	$ 442,600,000		$ 58,500,000
Stock repurchase program, authorized amount	$ 800,000,000.0						$ 300,000,000.0	$ 500,000,000.0
Canceled shares (in shares) | shares	4,000,000	14,800,000	14,800,000			1