Capital Stock (Detail) - shares	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Beginning balance	169,316,460	168,628,177
SARs exercised	0	77,002
Restricted stock grants	464,428	335,103
Restricted stock units vested	263,047	252,507
Shares retired	(739)
Treasury shares issued	14,511	23,671
Ending balance	247,100,456	169,316,460
Memorial
Class Of Stock [Line Items]
Memorial Merger	77,042,749	0