Shareholders' Equity, Noncontrolling Interests and Other Comprehensive Income - Common Shares, Share Repurchases and Dividends and Distributions (Details) - USD ($)			3 Months Ended		12 Months Ended
	Feb. 27, 2018	Nov. 08, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	May 10, 2017	May 09, 2017
Class of Stock [Line Items]
Common shares, authorized (in shares)			200,000,000		100,000,000	200,000,000	100,000,000
Authorized amount			$ 200,000,000.0
Number of shares repurchased during period (in shares)			1,304,194		0
Shares repurchased during period			$ 31,961,000
Remaining authorized repurchase amount			$ 168,000,000
Cash dividends declared per common share (in dollars per share)			$ 0.27	$ 0.26
Restricted Stock
Class of Stock [Line Items]
Restricted stock, shares canceled for tax withholding for share based compensation (in shares)			3,288		4,314
LTIP Units and Restricted Stock
Class of Stock [Line Items]
Unit based compensation					$ 8,400,000
Regular Quarterly Cash Dividend
Class of Stock [Line Items]
Cash dividends declared, period increase (in dollars per share)		$ 0.01
Cash dividends declared per common share (in dollars per share)	$ 0.27	$ 0.27