Quarterly Financial Data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data

	Quarters Ended
	December 31			September 30			June 30			March 31
2016
Operating revenue	$	18,747		$	27,192		$	29,551		$	20,254
Operating (loss) income	$	(881	)	$	1,595		$	2,143		$	(897	)
Net income attributable to the Company	$	2,709		$	2,711		$	1,810		$	8,665
Basic and diluted income per share attributable to the Company	$	0.04		$	0.04		$	0.02		$	0.11
2015
Operating revenue	$	21,104		$	27,830		$	37,846		$	17,091
Operating (loss) income	$	(3,861	)	$	(2,383	)	$	5,811		$	(5,702	)
Net (loss) income attributable to the Company	$	(2,541	)	$	2,772		$	(224	)	$	(1,738	)
Basic and diluted (loss) income per share attributable to the Company	$	(0.03	)	$	0.03		$	—		$	(0.02	)