Earnings per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator [Abstract]
Net income attributable to controlling interest	$ 17,743	$ 15,105
Denominator [Abstract]
Denominator for basic earnings per share (in shares)	22,965	22,904
Effect of dilutive securities [Abstract]
Employee stock options and restricted stock units (in shares)	106	145
Supplemental Executive Retirement Plan (in shares)	64	65
Denominator for diluted earnings per share (in shares)	23,135	23,114