CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Earnings in Excess of Distributions (Distributions in Excess of Earnings)	Accumulated Other Comprehensive Items, Net	Noncontrolling Interests	Redeemable Noncontrolling Interests	Over-Allotment Option [Member]	Over-Allotment Option [Member] Common Stock	Over-Allotment Option [Member] Additional Paid-in Capital	At The Market (ATM) Equity Program [Member]	At The Market (ATM) Equity Program [Member] Common Stock	At The Market (ATM) Equity Program [Member] Additional Paid-in Capital
Balance (in shares) at Dec. 31, 2017		283,110,183
Balance at Dec. 31, 2017	$ 2,298,842	$ 2,831	$ 4,164,562	$ (1,765,966)	$ (103,989)	$ 1,404
Increase (Decrease) in Stockholders' Equity
Issuance of shares under employee stock purchase plan and option plans and stock-based compensation (in shares)		364,736
Issuance of shares under employee stock purchase plan and option plans and stock-based compensation	1,432	$ 4	1,428
Change in value of redeemable noncontrolling interests			(117)
Issuance of shares								$ 76,192	$ 22	$ 76,170	$ 8,716	$ 2	$ 8,714
Issuance of shares (in shares)									2,175,000			273,486
Change in value of redeemable noncontrolling interests	(117)						$ 117
Parent cash dividends declared	(169,044)			(169,044)
Foreign currency translation adjustment	30,246				30,092	154
Change in Fair Value of Interest Rate Swap Agreements	(185)				(185)
Net income (loss)	45,152			44,684		(30)
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	44,654
Noncontrolling interests dividends	0
Balance at Mar. 31, 2018	$ 2,261,275	$ 2,859	4,250,757	(1,919,787)	(74,082)	1,528
Balance (in shares) at Mar. 31, 2018		285,923,405
Redeemable Noncontrolling Interest at Dec. 31, 2017							91,418
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary Equity, Foreign Currency Translation Adjustments							1,405
Temporary Equity, Net Income							498
Temporary Equity, Accretion of Dividends							(561)
Redeemable Noncontrolling Interest at Mar. 31, 2018							92,877
Balance (in shares) at Dec. 31, 2018	286,321,009	286,321,009
Balance at Dec. 31, 2018	$ 1,885,589	$ 2,863	4,263,348	(2,116,367)	(265,664)	1,409
Increase (Decrease) in Stockholders' Equity
Issuance of shares under employee stock purchase plan and option plans and stock-based compensation (in shares)		508,845
Issuance of shares under employee stock purchase plan and option plans and stock-based compensation	2,923	$ 5	2,918
Change in value of redeemable noncontrolling interests	(1,288)		(1,288)				1,288
Parent cash dividends declared	(176,460)			(176,460)
Foreign currency translation adjustment	17,378				17,378	0
Change in Fair Value of Interest Rate Swap Agreements	(2,674)				(2,674)
Net income (loss)	30,452
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	29,485			29,561		(76)
Noncontrolling interests dividends	0
Balance at Mar. 31, 2019	$ 1,760,734	$ 2,868	$ 4,264,978	(2,257,485)	$ (250,960)	$ 1,333
Balance (in shares) at Mar. 31, 2019	286,829,854	286,829,854
Redeemable Noncontrolling Interest at Dec. 31, 2018	$ 70,532						70,532
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary Equity, Foreign Currency Translation Adjustments							813
Temporary Equity, Net Income							967
Temporary Equity, Accretion of Dividends							(498)
Redeemable Noncontrolling Interest at Mar. 31, 2019	73,102						$ 73,102
Increase (Decrease) in Stockholders' Equity
Cumulative-effect adjustment for adoption of ASU 2014-09 (see Note 2.c.) | Accounting Standards Update 2016-02 [Member]	$ 5,781			$ 5,781