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, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income attributable to common stockholders		$ 43,622	$ 22,029	$ 35,699	$ 20,350	$ 65,651	$ 56,049
Weighted average common shares outstanding, basic (in shares)		67,022		66,578		66,931	66,679
Weighted average common shares outstanding, diluted (in shares)		67,564		67,077		67,604	67,179
Basic income per common share (in dollars per share)		$ 0.65		$ 0.54		$ 0.98	$ 0.84
Diluted income per common share (in dollars per share)		$ 0.65		$ 0.53		$ 0.97	$ 0.83
Restricted stock units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)	[1]	454		390		562	403
Stock options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock based payment arrangements (in shares)		88		109		111	97

[1] Includes service-based and contingently issuable performance-based restricted stock units.