Earnings Per Share (Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income attributable to common stockholders	$ 20,350	$ 15,359
Weighted average common shares outstanding, basic (in shares)	66,782	67,138
Weighted average common shares outstanding, diluted (in shares)	67,282	67,664
Basic income per common share (in dollars per share)	$ 0.30	$ 0.23
Diluted income per common share (in dollars per share)	$ 0.30	$ 0.23
Restricted stock units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	415	299
Stock options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	85	172
Restricted stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	0	55