Shareholders' Equity - Changes in Shareholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 957,456	$ 1,026,904	$ 996,048	$ 1,039,904
Proceeds from exercise of stock options		739	1	1,072
Stock-based compensation expense	4,706	5,453	14,474	12,180
Dividends paid	(58,457)	(58,177)	(116,160)	(116,122)
Other adjustment to additional paid-in capital	273		9,198
Purchase of treasury shares	(273)		(9,282)
Shares withheld for net settlements of share- based awards	(156)		(2,789)	(4,172)
Issuance of common stock - ESPP	146	128	296	252
Net income (loss)	36,654	41,836	61,775	82,485
Other comprehensive income (loss)	3,946	4,654	(9,266)	6,902
Ending Balance	944,295	1,021,538	944,295	1,021,538
Accounting Standards Update 2016-02
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Other comprehensive income (loss)		4,655		5,939
Common shares
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 1,262	$ 1,254	$ 1,254	$ 1,248
Beginning Balance (shares)	121,386	121,187	121,225	120,585
Proceeds from exercise of stock options (shares)		42		64
Restricted stock granted			$ 9	$ 8
Restricted stock granted (shares)		10	900	788
Restricted stock canceled (shares)	(5)	(32)	(27)	(38)
Purchase of treasury shares (in shares)	(23)		(577)
Shares withheld for net settlements of share- based awards			$ (1)	$ (2)
Shares withheld for net settlements of share-based awards (shares)			(173)	(198)
Issuance of common stock - ESPP (shares)	13	6	23	12
Ending Balance	$ 1,262	$ 1,254	$ 1,262	$ 1,254
Ending Balance (shares)	121,371	121,213	121,371	121,213
Additional Paid-In Capital
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 1,247,068	$ 1,213,922	$ 1,230,865	$ 1,210,916
Proceeds from exercise of stock options		739	1	1,072
Stock-based compensation expense	4,706	5,453	14,474	12,180
Restricted stock granted			(9)	(8)
Other adjustment to additional paid-in capital	273		9,198
Shares withheld for net settlements of share- based awards	(156)		(2,788)	(4,170)
Issuance of common stock - ESPP	146	128	296	252
Ending Balance	1,252,037	1,220,242	1,252,037	1,220,242
Distributions in Excess of Earnings
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	(152,301)	(71,076)	(119,779)	(52,868)
Dividends paid	(58,457)	(58,177)	(116,160)	(116,122)
Net income (loss)	36,720	41,914	61,901	82,619
Ending Balance	(174,038)	(87,339)	(174,038)	(87,339)
Distributions in Excess of Earnings | Cumulative Effect Period of Adoption Adjustment | Accounting Standards Update 2018-02
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance				(968)
Accumulated Other Comprehensive Loss
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	(33,499)	(21,366)	(20,335)	(23,618)
Other comprehensive income (loss)	3,945		(9,219)
Ending Balance	(29,554)	(16,716)	(29,554)	(16,716)
Accumulated Other Comprehensive Loss | Accounting Standards Update 2016-02
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Other comprehensive income (loss)		4,650		5,934
Accumulated Other Comprehensive Loss | Cumulative Effect Period of Adoption Adjustment | Accounting Standards Update 2018-02
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance				968
Treasury shares
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ (104,184)	$ (95,175)	$ (95,175)	$ (95,175)
Beginning Balance (shares)	4,764	4,210	4,210	4,210
Purchase of treasury shares	$ (273)		$ (9,282)
Purchase of treasury shares (in shares)	23		577
Ending Balance	$ (104,457)	$ (95,175)	$ (104,457)	$ (95,175)
Ending Balance (shares)	4,787	4,210	4,787	4,210
Noncontrolling Interests
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ (890)	$ (655)	$ (782)	$ (599)
Net income (loss)	(66)	(78)	(126)	(134)
Other comprehensive income (loss)	1		(47)
Ending Balance	$ (955)	(728)	$ (955)	(728)
Noncontrolling Interests | Accounting Standards Update 2016-02
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Other comprehensive income (loss)		$ 5		$ 5