Dividends (Tables)

12 Months Ended

Dec. 31, 2017

Dividends [Abstract]

Summary of dividends declared and paid per share

The following table provides a summary of dividends declared and paid per share:

	Year Ended December 31,
	2017				2016				2015
	Declared		Paid		Declared		Paid		Declared		Paid
Common shares	$	3.960	$	3.940	$	3.840	$	3.800	$	3.620	$	3.550
5.417% Series 1 Cumulative Convertible Preferred shares	$	1.354	$	1.354	$	1.354	$	1.354	$	1.354	$	1.354
5.0% Series C Cumulative Redeemable Preferred shares (1)	$	0.368	$	—	$	—	$	—	$	—	$	—
(1) Amount represents dividends per depository share, each representing 1/1000th of a share.

Summary of income tax status of dividends per share paid

A summary of the income tax status of dividends per share paid is as follows:

	Year Ended December 31,
	2017		2016		2015
Common shares
Ordinary dividend	$	3.940	$	3.800	$	3.515
Capital gain	—		—		0.035
	$	3.940	$	3.800	$	3.550
5.417% Series 1 Cumulative Convertible Preferred shares
Ordinary dividend	$	1.354	$	1.354	$	1.340
Capital gain	—		—		0.014
	$	1.354	$	1.354	$	1.354