Stockholders' Equity Share Repurchase Program (Details) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 10, 2015
Class of Stock [Line Items]
Stock repurchased during period, value	$ 150,300,000
Class A and Class B common stock
Class of Stock [Line Items]
Stock repurchase program, authorized amount		$ 1,000,000,000
Common stock issued, Class B
Class of Stock [Line Items]
Stock repurchased during period, shares	2.0
Stock repurchased during period, value	$ 150,000,000