Shareholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance			$ 1,006,837
Proceeds from exercise of stock options, value			$ 2,367
Proceeds from exercise of stock options, shares			108
Tax deficiency related to equity compensation			$ (844)
Stock-based compensation expense			9,675
Restricted stock granted, value			0
Restricted stock canceled			0
Dividends paid			(145,990)
Shares withheld for net settlements of share-based awards			(2,336)
Other adjustments to additional paid-in-capital			179
Issuance of common stock (ESPP), value			338
Net income	$ 43,674	$ 38,291	99,156	$ 95,295
Other comprehensive (loss) income	483	$ (6,441)	(2,983)	$ (7,315)
Ending Balance	966,399		966,399
Common shares
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance			$ 747
Beginning Balance, shares			74,643
Proceeds from exercise of stock options, value			$ 0
Proceeds from exercise of stock options, shares			108
Restricted stock granted, value			$ 3
Restricted stock granted, shares			349
Restricted stock canceled			$ 0
Restricted stock canceled (shares)			(51)
Shares withheld for net settlements of share-based awards (shares)			(75)
Issuance of common stock (ESPP), shares			12
Ending Balance	$ 750		$ 750
Ending Balance, shares	74,986		74,986
Additional Paid-In Capital
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance			$ 879,599
Proceeds from exercise of stock options, value			2,367
Tax deficiency related to equity compensation			(844)
Stock-based compensation expense			9,675
Restricted stock granted, value			(3)
Shares withheld for net settlements of share-based awards			(2,336)
Other adjustments to additional paid-in-capital			179
Issuance of common stock (ESPP), value			338
Ending Balance	$ 888,975		888,975
Earnings in Excess of Distributions
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance			158,796
Dividends paid			(145,990)
Net income			99,279
Other comprehensive (loss) income			0
Ending Balance	112,085		112,085
Accumulated Other Comprehensive Loss
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance			(32,404)
Other comprehensive (loss) income			(3,002)
Ending Balance	(35,406)		(35,406)
Noncontrolling Interests
Changes in shareholders' equity that are attributable to the Company's shareholders and to non controlling interests
Beginning Balance			99
Net income			(123)
Other comprehensive (loss) income			19
Ending Balance	$ (5)		$ (5)