Contingencies (Details) - Shareholder class action lawsuits - item		6 Months Ended
	Aug. 30, 2013	Jun. 30, 2016
Contingencies
Number of notices of actions relating to Canadian securities class action claims		3
Number of actions were succeeded by specific action with an amended claim	3
Number of actions by which specific Ontario actions were succeeded	1
Number of pending matters having material adverse impact on financial position or results of operations or have been reserved		0