Capital Stock and Share Based Compensation Plans - Narrative (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) director common_share $ / shares shares	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	May. 31, 2014 USD ($)
Class of Stock [Line Items]
Classes of common shares | common_share	2
Minimum number of directors up for election to entitle shareholders to vote | director	3
Minumum percent of directors up for election to entitle shareholders to vote	33.33%
Stock repurchased during period, value	$ 16,222,000	$ 21,237,000	$ 74,199,000
Number of shares available for future stock compensation grants | shares	5,500,000.0
Total unrecognized compensation cost related to restricted stock, RSUs and performance shares	$ 6,900,000
Stock Options | Common stock, Class A | Maximum
Class of Stock [Line Items]
Purchase price of stock options granted, percent of fair market value	100.00%
Restricted Stock and Restricted Stock Units | Minimum
Class of Stock [Line Items]
Vesting period of stock options	3 years
Restricted Stock and Restricted Stock Units | Maximum
Class of Stock [Line Items]
Vesting period of stock options	4 years
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Weighted-average period of recognition, years	2 years 1 month
First Repurchase Plan | Minimum
Class of Stock [Line Items]
Range of price of shares repurchased | $ / shares	$ 15.92
First Repurchase Plan | Maximum
Class of Stock [Line Items]
Range of price of shares repurchased | $ / shares	$ 24.96
First Repurchase Plan | Common stock, Class A
Class of Stock [Line Items]
Stock repurchase program, authorized amount				$ 100,000,000
Stock repurchased during period, value	$ 16,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 84,000,000