Equity Based Compensation Stock Option and SAR Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Options and SARs outstanding, beginning of year (shares)	4,191,007	2,568,383	3,032,143
Granted (shares)	1,497,400	2,460,500	347,800
Exercised (shares)	(1,286,527)	(303,049)	(68,510)
Forfeited (shares)	(827,775)	(534,827)	(743,050)
Options and SARs outstanding, end of year (shares)	3,574,105	4,191,007	2,568,383
Vested options and SARS exercisable, December 31, 2018 (shares)	768,955
Weighted-Average Strike Price
Options and SARs Outstanding, weighted-average exercise price, Beginning of year (usd per share)	$ 26.71	$ 26.56	$ 28.60
Granted, weighted-average exercise price (usd per share)	43.49	25.95	16.26
Exercised, weighted-average exercise price (usd per share)	30.55	17.04	14.69
Forfeited,weighted-average exercise price (usd per share)	29.01	28.00	31.17
Options and SARs Outstanding, weighted-average exercise price, End of year (usd per share)	32.67	$ 26.71	$ 26.56
Vested options and SARS exercisable, December 31, 2018, weighted-average exercise price (usd per share)	$ 26.40
Options and SARs outstanding, December 31, 2018, weighted-average contractual term (usd per share)	8 years 4 months 24 days
Vested options and SARs exercisable, December 31, 2018, weighted-average contractual term (year)	6 years 8 months 12 days
Options and SARs outstanding, December 31, 2018, average intrinsic value (year)	$ 42.7
Vested options and SARs exercisable, December 31, 2018, average intrinsic value (usd per share)	$ 4.7