Capital Stock (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class A
Common stock
Minimum multiplier for dividend payable on Class A common stock per dividend declared on Class B common stock (as a percent)	67.00%
Class B
Common stock
Percentage of dividend declared on Class B common stock used to determine dividend payable on Class A common stock (as a percent)	67.00%
Ratio for converting shares of Class B common stock into shares of Class A common stock (as a percent)	2400.00%	2400.00%
Class B common stock shares converted into Class A common stock shares (in shares)	0	0	0