Share Capital - Changes in Number of Shares of Class A Stock Outstanding (Detail) (Class A Stock [Member])	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Oct. 07, 2011
Class A Stock [Member]
Class of Stock [Line Items]
Class A Stock outstanding, beginning of year	13,516,626	13,508,318	13,377,967	13,508,318	13,572,265
Issued pursuant to shared-based compensation plans	2,500		141,159	0
Class A Stock outstanding, end of year	13,519,126	13,496,783	13,519,126	13,496,783	13,572,265
Stock Repurchased and Retired During Period, Shares		(11,535)		(11,535)