Earnings Per Share (Summary Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net income attributable to common stockholders	$ 18,086	$ 11,735	$ 25,241	$ 18,096
Less: adjustment for income allocated to participating securities	(2,843)	(1,857)	(3,971)	(2,868)
Net income attributable to common stockholders - basic and diluted	$ 15,243	$ 9,878	$ 21,270	$ 15,228
Denominator:
Weighted average common shares outstanding - basic (shares)	73,953	73,389	73,882	73,238
Plus: dilutive effect of stock options and unvested restricted stock units (shares)	619	854	743	1,151
Weighted average common shares outstanding - diluted (shares)	74,572	74,243	74,625	74,389
Net income per common share:
Basic (in dollars per share)	$ 0.21	$ 0.13	$ 0.29	$ 0.21
Diluted (in dollars per share)	$ 0.20	$ 0.13	$ 0.29	$ 0.20