Earnings per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator [Abstract]
Net income (loss) attributable to controlling interest	$ 23,377	$ (40,674)	$ 37,651	$ (20,407)
Denominator [Abstract]
Denominator for basic earnings per share (in shares)	22,509	23,061	22,503	23,053
Effect of dilutive securities [Abstract]
Restricted stock units (in shares)	110	0	105	0
Supplemental Executive Retirement Plan (in shares)	48	0	48	0
Denominator for diluted earnings per share (in shares)	22,667	23,061	22,656	23,053