Stockholders' Equity and Compensation Arrangements Initial Public Offering, Convertible Preferred Stock and Common Stock (Details) $ in Millions		9 Months Ended
	Oct. 31, 2016 class	Sep. 30, 2017 USD ($) class shares	Dec. 31, 2016 shares
Preferred Stock, Shares Outstanding		0	0
Preferred Stock, Shares Authorized		50,000,000
Classes of common stock, number | class	3	1
Common Stock [Member]
Common Stock, Shares Authorized		2,010,000,000	2,010,000,000
Common Class A [Member]
Stock Repurchase Program, Authorized Amount | $		$ 700.0