Consolidated Statement Of Changes In Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-in Capital [Member]	Treasury shares [Member]	Accumulated other comprehensive income (loss) [Member]	Distributions in excess of net income [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total equity	$ 2,185,901	$ 663	$ 139	$ 2,677,046	$ (113,172)	$ 7,734	$ (386,509)
Balance (in shares) at Dec. 31, 2016		66,263,487	13,849,050
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Changes During Period Shares		19,030
Issuance of nonvested shares, net		295,754
Issuance of nonvested shares, net	(5,498)	$ (3)		(5,585)	90
Purchase of common shares for vesting	6,729				6,729
Amortization of nonvested shares	(10,038)			(10,038)
Share option expense	528			528
Foreign currency translation adjustment	13,539					13,539
Change in unrealized gain/loss on derivatives	(10,354)					(10,354)
Net income	197,405						197,405
Issuances of common shares (in shares)		939,472
Issuances of common shares	68,748	$ 9		68,739
Stock Issued During Period, Shares, Acquisitions		8,851,264
Stock Issued During Period, Value, Acquisitions	657,473	$ 89		657,384
Stock Issued During Period, Shares, Conversion of Convertible Securities		381
Stock Redeemed or Called During Period, Shares			(835)
Stock Redeemed or Called During Period, Value	$ (1)		$ (1)
Stock option exercises, net (in shares)	28,281	28,281
Stock option exercises, net	$ (1)	$ 0		(1,547)	(1,548)
Dividends to common and preferred shareholders	(233,737)						(233,737)
Balance (in shares) at Sep. 30, 2017		76,397,669	13,848,215
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total equity	$ 2,888,308	$ 764	$ 138	$ 3,420,867	$ (121,539)	$ 10,919	$ (422,841)