Earnings Per Share (Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income attributable to common stockholders	$ 15,359	$ 3,744
Weighted average common shares outstanding, basic (in shares)	67,138	66,692
Weighted average common shares outstanding, diluted (in shares)	67,664	67,186
Basic income per common share (in dollars per share)	$ 0.23	$ 0.06
Diluted income per common share (in dollars per share)	$ 0.23	$ 0.06
Restricted stock units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	299	178
Stock options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	172	233
Restricted stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	55	83