Capital Stock (Details) - USD ($)					1 Months Ended				6 Months Ended	12 Months Ended
	Nov. 12, 2013	Sep. 22, 2010	Nov. 11, 2009	Sep. 16, 2009	Jan. 31, 2017	Nov. 30, 2013	Sep. 30, 2006	Jun. 30, 2004	Dec. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014	Nov. 30, 2001
Stock-based compensation disclosure
Compensation expense									$ 8,100,000	$ 21,900,000	$ 15,300,000	$ 15,600,000
Aggregate number of common shares reserved for future issuance									19,700,000
Proceeds from stock options exercised										$ 5,161,000	4,429,000	9,136,000
Stock options
Stock-based compensation disclosure
Stock options granted to directors (in shares)									3,536,000	3,340,000
Options exercised (in shares)									0	555,000
Proceeds from stock options exercised										$ 5,161,000	$ 4,429,000	$ 9,136,000
Exercisable at the end of the period (in shares)									7,898,000	6,453,000	5,380,000	4,637,000
Weighted-Average Exercise Price (in dollars per share)									$ 13.15	$ 12.63	$ 11.89	$ 9.79
Deferred share units
Stock-based compensation disclosure
Compensation expense									$ 215,000	$ 380,000	$ 389,000	$ 433,000
2001 Director Plan
Stock-based compensation disclosure
Aggregate number of common shares reserved for future issuance													50,000
2001 Director Plan | Deferred share units
Stock-based compensation disclosure
Compensation expense									$ (7,000)	$ (72,000)	$ 16,000	$ (30,000)
Stock units issued (in shares)									0	0	0	0
Stock units outstanding (in shares)									6,000	6,000	6,000	6,000
2004 Director Plan | Deferred share units
Stock-based compensation disclosure
Vesting period							3 years
Monthly vesting rights (as a percent)								8.30%
Compensation Policy for Non-Employee Directors | Stock options
Stock-based compensation disclosure
Stock options granted to directors (in shares)									40,000	80,000	80,000	80,000
Grant date fair value		$ 30,000
Compensation Policy for Non-Employee Directors | Deferred share units
Stock-based compensation disclosure
Compensation expense									$ 215,000	$ 380,000	$ 389,000	$ 433,000
Stock units issued (in shares)					53,248	43,615			37,000	41,000	31,000	28,000
Vesting period	1 year			1 year
Common stock issued when a director ceases to be a member (in shares)			1
Stock units previously granted (in shares)									12,000	12,000	15,000	19,000
Non-employee directors-initial grant | Deferred share units
Stock-based compensation disclosure
Vesting period			3 years
Grant date fair value			$ 65,000
Non-employee directors-first anniversary | Deferred share units
Stock-based compensation disclosure
Grant date fair value			$ 30,000
Non-employee directors-after year one | Deferred share units
Stock-based compensation disclosure
Vesting period			1 year
Grant date fair value			$ 30,000