Capital Stock (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended	12 Months Ended
	Feb. 28, 2018	Dec. 09, 2016	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 20, 2016
Class of Warrant or Right [Line Items]
Shares Issued, Price Per Share							$ 5.15	$ 5.50		$ 11.43
Proceeds from Issuance of Common Stock		$ 109,700	$ 60,200	$ 274		$ 152,657
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 5.75
Warrants liability							$ 2,073		$ 13,202
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							11,200,000
Fair Value Adjustment of Warrants				$ (11,129)	$ (5,301)	$ 2,106
Warrants Issuance Cost charged to Earnings					$ 900
Total number of new units issued	7,772,021			7,772,021	0	33,810,000
Issuance Costs, Warrants					$ 6,500
underwriters option to purchase				2,900,000
per share net of underwrtiter discount			$ 5.2525	$ 4.9183
Common Stock, Shares, Issued		22,300,000					128,455,134	11,500,000	118,515,797
Unitssubjecttounderwritersoption								1,500,000
Common stock, shares authorized							250,000,000		250,000,000
Common stock, par value (in dollars per share)							$ 0.01		$ 0.01
Preferred stock, shares authorized							5,000,000
Preferred stock, par value							$ 0.01
Common Stock, Shares, Outstanding			114,985,072	115,877,704	114,985,072	80,256,544	125,737,565		115,877,704
Treasury stock, shares held			2,536,421	2,638,093	2,536,421	2,281,495	2,717,569		2,638,093
Common Shares Outstanding and Treasury Shares Held Rollforward [Table]
Common shares outstanding, beginning balance			114,985,072	115,877,704	114,985,072	80,256,544
Exercise of common stock options, net				65,524	0	636,937
Grants of restricted stock, net				2,022,316	892,632	281,591
Common shares outstanding, ending balance				125,737,565	115,877,704	114,985,072
Treasury stock, beginning balance			2,536,421	2,638,093	2,536,421	2,281,495
Shares received upon exercise of common stock options				0	0	13,854
Shares received upon vesting of restricted stock, net				79,476	101,672	241,072
Treasury stock, ending balance				2,717,569	2,638,093	2,536,421
Amount authorized under stock repurchase program							$ 20,000