Shareholders' Equity - Changes in Shareholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 944,295	$ 1,021,538	$ 996,048	$ 1,039,904
Proceeds from exercise of stock options		182	1	1,259
Stock-based compensation expense	4,689	4,739	19,163	16,919
Dividends paid	(58,527)	(58,200)	(174,687)	(174,322)
Other adjustment to additional paid-in capital	280		9,479
Purchase of treasury shares	(280)		(9,562)
Shares withheld for net settlements of share- based awards		(2)	(2,789)	(4,177)
Issuance of common stock - ESPP	170	150	465	400
Net income (loss)	39,172	45,885	100,947	128,370
Other comprehensive income (loss)	2,485	(7,288)	(6,781)	(381)
Ending Balance	932,284	1,007,004	932,284	1,007,004
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)				(1,349)
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)	121,371	121,213	121,225	120,585
Proceeds from exercise of stock options		$ 1		$ 1
Proceeds from exercise of stock options (shares)		15		78
Restricted stock granted			$ 9	$ 8
Restricted stock granted (shares)		0	900	788
Restricted stock canceled		$ (1)
Restricted stock canceled (shares)	(22)	(14)	(49)	(52)
Purchase of treasury shares (in shares)	(25)		(602)
Shares withheld for net settlements of share- based awards			$ (1)	$ (2)
Shares withheld for net settlements of share-based awards (shares)	(1)	(1)	(174)	(198)
Issuance of common stock - ESPP		$ 1
Issuance of common stock - ESPP (shares)	16	9	39	21
Ending Balance	$ 1,262	$ 1,255	$ 1,262	$ 1,255
Ending Balance (shares)	121,339	121,222	121,339	121,222
Additional Paid-In Capital
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 1,252,037	$ 1,220,242	$ 1,230,865	$ 1,210,916
Proceeds from exercise of stock options		181	1	1,258
Stock-based compensation expense	4,689	4,739	19,163	16,919
Restricted stock granted			(9)	(8)
Restricted stock canceled		1
Other adjustment to additional paid-in capital	280		9,479
Shares withheld for net settlements of share- based awards		(2)	(2,788)	(4,175)
Issuance of common stock - ESPP	170	149	465	400
Ending Balance	1,257,176	1,225,310	1,257,176	1,225,310
Distributions in Excess of Earnings
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	(174,038)	(87,339)	(119,779)	(52,868)
Dividends paid	(58,527)	(58,200)	(174,687)	(174,322)
Net income (loss)	39,220	45,932	101,121	128,551
Ending Balance	(193,345)	(99,607)	(193,345)	(99,607)
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	(29,554)	(16,716)	(20,335)	(23,618)
Other comprehensive income (loss)	2,481	(7,273)	(6,738)
Ending Balance	(27,073)	(23,989)	(27,073)	(23,989)
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)				(1,339)
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	$ (104,457)	$ (95,175)	$ (95,175)	$ (95,175)
Beginning Balance (shares)	4,787	4,210	4,210	4,210
Purchase of treasury shares	$ (280)		$ (9,562)
Purchase of treasury shares (in shares)	25		602
Ending Balance	$ (104,737)	$ (95,175)	$ (104,737)	$ (95,175)
Ending Balance (shares)	4,812	4,210	4,812	4,210
Noncontrolling Interests
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ (955)	$ (728)	$ (782)	$ (599)
Net income (loss)	(48)	(47)	(174)	(181)
Other comprehensive income (loss)	4	(15)	(43)
Ending Balance	$ (999)	$ (790)	$ (999)	(790)
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)				$ (10)