Capital Stock (Tables)

12 Months Ended

Dec. 31, 2017

Capital Stock [abstract]

Capital stock

The following table presents information regarding capital stock:

	December 31,
(in thousands)	2017	2016
Class A common stock authorized	1,000,000	1,000,000
Class A common stock issued and outstanding	339,235	338,240
Class B-1 common stock authorized, issued and outstanding	0.6	0.6
Class B-2 common stock authorized, issued and outstanding	0.8	0.8
Class B-3 common stock authorized, issued and outstanding	1.3	1.3
Class B-4 common stock authorized, issued and outstanding	0.4	0.4