Common Stock (Tables)

12 Months Ended

Dec. 31, 2016

Common Stock.

Summary of the cost and number of Class A common stock repurchased

	Year Ended December 31,
	2016			2015
	Number of shares	Cost of shares		Number of shares	Cost of shares
	repurchased	repurchased		repurchased	repurchased
	(amounts in millions, except share amount)
Stock repurchase programs:
April 30, 2013	—	$	—	497,010	$	27.3
July 27, 2015	501,229		26.8	315,530		17.3
Total	501,229	$	26.8	812,540	$	44.6