Shareholders' Equity Rollforward (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	$ 185,548
Net income (loss)	28,407
All Other Changes	835
As of ending balance	214,790
Share-based compensation	846
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	150
As of ending balance	150
Paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	190,621
All Other Changes	835	[1]
As of ending balance	191,456
Retained earnings (accumulated deficit)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	(5,296)
Net income (loss)	28,407
As of ending balance	23,111
Accumulated other comprehensive income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	73
As of ending balance	$ 73

[1] ncludes equity-classified share-based compensation of $846.