Earnings Per Share (Basic and Diluted EPS) (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
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income (loss) attributable to common stockholders	$ 17,596	$ 17,982	$ 21,340	$ 11,226
Weighted average common shares outstanding, basic (in shares)	66,927	65,839	66,810	65,589
Weighted average common shares outstanding, diluted (in shares)	67,394	66,417	67,290	66,137
Basic income (loss) per common share (in dollars per share)	$ 0.26	$ 0.27	$ 0.32	$ 0.17
Diluted income (loss) per common share (in dollars per share)	$ 0.26	$ 0.27	$ 0.32	$ 0.17
Restricted stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	61	229	72	258
Restricted stock units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	210	117	194	66
Stock options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	196	232	214	224