Shareholders' Equity (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Activities Under Share Repurchase Program

The following table provides activities under the share repurchase program:

	For the three months ended March 31
	2018		2017
Number of Common Shares repurchased(1)	1,435,700		—
Weighted-average price per share(2)	$	221.76	$	—
Amount of repurchase (in millions)(2)	$	318	$	—

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

⁽²⁾ Includes brokerage fees.