Earnings (Loss) per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator [Abstract]
Net income (loss) attributable to controlling interest	$ 6,995	$ (2,667)	$ (13,411)	$ 26,873
Denominator [Abstract]
Denominator for basic earnings (loss) per share (in shares)	22,923	23,029	23,009	23,023
Effect of dilutive securities [Abstract]
Restricted stock units (in shares)	104	0	0	94
Supplemental Executive Retirement Plan (in shares)	57	0	0	63
Denominator for diluted earnings (loss) per share (in shares)	23,084	23,029	23,009	23,180