Capital Stock and Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Summary of calculation of diluted earnings (loss) per share

		2017		2016		2015
Numerator for calculation of basic earnings (loss) per share:
	Net income (loss)	$	(6,639)	$	21,841	$	(204,900)
Denominator for basic income (loss) per share:
	Weighted-average shares outstanding		72,907		61,328		61,053
Basic earnings (loss) per share		$	(0.09)	$	0.36	$	(3.36)
Numerator for calculation of diluted earnings (loss) per share:
	Net income (loss)	$	(6,639)	$	21,841	$	(204,900)
Denominator for diluted earnings (loss) per share:
	Weighted-average shares outstanding		72,907		61,328		61,053
Dilutive effect of stock equivalents			—		962		—
Denominator for diluted earnings (loss) per share			72,907		62,290		61,053
Diluted earnings (loss) per share		$	(0.09)	$	0.35	$	(3.36)

Schedule of anti-dilutive securities excluded from diluted earnings (loss) per share calculation

	2017	2016	2015
Anti-dilutive stock equivalents	3,770	1,706	2,276