Share Capital (Tables)

12 Months Ended

Dec. 31, 2017

SHARE CAPITAL.

Schedule of share repurchase activities

($ millions, except as noted)		2017	2016
Share repurchase activities (thousands of common shares)
	Shares repurchased	33 154	—
Amounts charged to
	Share capital	536	—
	Retained earnings	877	—
Share repurchase cost		1 413	—
Average repurchase cost per share		42.61	—

Schedule of liability for share repurchases

($ millions)		December 31 2017	December 31 2016
Amounts charged to
	Share capital	97	—
	Retained earnings	180	—
Liability for share purchase commitment		277	—