Shareholders' Equity (Tables)

6 Months Ended

Jun. 30, 2018

Equity [Abstract]

Activities Under Share Repurchase Program

The following table describes activities under the share repurchase program:

	For the three months ended June 30				For the six months ended June 30
	2018		2017		2018		2017
Number of Common Shares repurchased(1)	1,060,262		682,900		2,495,962		682,900
Weighted-average price per share(2)	$	226.97	$	208.75	$	223.97	$	208.75
Amount of repurchase (in millions)(2)	$	241	$	143	$	559	$	143

⁽¹⁾ Includes shares repurchased but not yet canceled at quarter end.

⁽²⁾ Includes brokerage fees.