Shareholders' Equity - Changes in Shareholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 1,021,538	$ 1,092,937	$ 1,039,904	$ 1,198,919
Proceeds from exercise of stock options	182	409	$ 1,259	1,781
Proceeds from exercise of stock options (shares)			78
Stock-based compensation expense	4,739	5,564	$ 16,919	16,351
Restricted stock granted		0	0	0
Restricted stock canceled	0	0	0	0
Dividends paid	(58,200)	(57,239)	(174,322)	(172,256)
Shares withheld for net settlements of share-based awards	(2)	(61)	(4,177)	(4,452)
Issuance of common stock - ESPP	150	140	400	404
Repurchases of common stock				(70,446)
Net income (loss)	45,885	39,229	128,370	111,474
Other comprehensive income (loss)	(7,288)	(567)	(381)	(1,363)
Other comprehensive income (loss)			(1,349)
Ending Balance	1,007,004	1,080,412	1,007,004	1,080,412
Common shares
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 1,254	$ 1,248	$ 1,248	$ 1,240
Beginning Balance (shares)	121,213	121,677	120,585	124,008
Proceeds from exercise of stock options	$ 1		$ 1	$ 1
Proceeds from exercise of stock options (shares)	15	20	78	97
Restricted stock granted			$ 8	$ 9
Restricted stock granted (shares)		9	788	905
Restricted stock canceled	$ (1)
Restricted stock canceled (shares)	(14)	(24)	(52)	(52)
Shares withheld for net settlements of share-based awards			$ (2)	$ (2)
Shares withheld for net settlements of share-based awards (shares)	(1)	(2)	(198)	(173)
Issuance of common stock - ESPP	$ 1
Issuance of common stock - ESPP (shares)	9	6	21	18
Repurchases of common stock (shares)				(3,117)
Ending Balance	$ 1,255	$ 1,248	$ 1,255	$ 1,248
Ending Balance (shares)	121,222	121,686	121,222	121,686
Additional Paid-In Capital
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ 1,220,242	$ 1,198,930	$ 1,210,916	$ 1,190,906
Proceeds from exercise of stock options	181	409	1,258	1,780
Stock-based compensation expense	4,739	5,564	16,919	16,351
Restricted stock granted			(8)	(9)
Restricted stock canceled	1
Shares withheld for net settlements of share-based awards	(2)	(61)	(4,175)	(4,450)
Issuance of common stock - ESPP	149	140	400	404
Ending Balance	1,225,310	1,204,982	1,225,310	1,204,982
Earnings in Excess of Distributions
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	(87,339)	(11,068)	(52,868)	31,541
Dividends paid	(58,200)	(57,239)	(174,322)	(172,256)
Net income (loss)	45,932	39,289	128,551	111,697
Ending Balance	(99,607)	(29,018)	(99,607)	(29,018)
Accumulated Other Comprehensive Loss
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	(16,716)	(25,229)	(23,618)	(24,446)
Other comprehensive income (loss)	(7,273)	(556)		(1,339)
Other comprehensive income (loss)			(1,339)
Ending Balance	(23,989)	(25,785)	(23,989)	(25,785)
Treasury shares
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ (95,175)	$ (70,446)	$ (95,175)	$ 0
Beginning Balance (shares)	4,210	3,117	4,210	0
Repurchases of common stock				$ (70,446)
Repurchases of common stock (shares)				3,117
Ending Balance	$ (95,175)	$ (70,446)	$ (95,175)	$ (70,446)
Ending Balance (shares)	4,210	3,117	4,210	3,117
Noncontrolling Interests
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance	$ (728)	$ (498)	$ (599)	$ (322)
Net income (loss)	(47)	(60)	(181)	(223)
Other comprehensive income (loss)	(15)	(11)		(24)
Other comprehensive income (loss)			(10)
Ending Balance	$ (790)	$ (569)	$ (790)	$ (569)
Accounting Standards Update 2018-02
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Transition adjustment for accounting standard adoption					$ 0
Accounting Standards Update 2018-02 | Earnings in Excess of Distributions
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Transition adjustment for accounting standard adoption					(968)
Accounting Standards Update 2018-02 | Accumulated Other Comprehensive Loss
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Transition adjustment for accounting standard adoption					$ 968