CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	1 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Common shares, par value	$ 0.10	$ 0.10	$ 0.10
Common shares, shares authorized	600,000,000	600,000,000	600,000,000
Common shares, shares issued	367,149,127	367,149,127	366,298,335
Treasury at cost	666,209	666,209	947,893
Class A Cumulative Redeemable Preferred Shares [Member]
Cumulative redeemable preferred shares, liquidation value	$ 500.00	$ 500.00
Cumulative redeemable preferred shares, shares authorized	750,000	750,000
Cumulative redeemable preferred shares, shares issued	350,000	350,000
Cumulative redeemable preferred shares, shares outstanding	350,000	350,000
Preferred stock dividend rate	6.375%	6.375%
Cumulative redeemable preferred shares, par value
Class J Cumulative Redeemable Preferred Shares [Member]
Cumulative redeemable preferred shares, liquidation value	$ 500	$ 500	$ 500
Cumulative redeemable preferred shares, shares authorized	750,000	750,000	750,000
Cumulative redeemable preferred shares, shares issued	400,000	400,000	400,000
Cumulative redeemable preferred shares, shares outstanding	400,000	400,000	400,000
Preferred stock dividend rate		6.50%	6.50%
Cumulative redeemable preferred shares, par value
Class K Cumulative Redeemable Preferred Shares [Member]
Cumulative redeemable preferred shares, liquidation value	$ 500	$ 500	$ 500
Cumulative redeemable preferred shares, shares authorized	750,000	750,000	750,000
Cumulative redeemable preferred shares, shares issued	300,000	300,000	300,000
Cumulative redeemable preferred shares, shares outstanding	300,000	300,000	300,000
Preferred stock dividend rate		6.25%	6.25%
Cumulative redeemable preferred shares, par value