Condensed Consolidated Statements of Changes in Redeemable Convertible Preferred Stock and Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total		Series B Redeemable Convertible Preferred Stock [Member]	Convertible Series A Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated earnings [Member]
Beginning Balance at Dec. 31, 2015	$ 9,778				$ 2	$ 107,757	$ (97,981)
Beginning Balance, Shares at Dec. 31, 2015				1,000,000	206,168,035
Preferred Stock Value, Beginning Balance at Dec. 31, 2015			$ 502,213
Preferred Stock Beginning Balance, Shares at Dec. 31, 2015			600,000
Net income	201,700						201,700
Redeemable convertible series B preferred stock dividends	(18,000)		$ (18,000)				(18,000)
Issuance of common stock under restricted stock compensation arrangement, Shares					212,765
Equity-based compensation	658					658
Ending Balance at Dec. 31, 2016	194,136	[1]			$ 2	108,415	85,719
Ending Balance, Shares at Dec. 31, 2016				1,000,000	206,380,800
Preferred Stock Value, Ending Balance at Dec. 31, 2016			$ 502,213
Preferred Stock Ending Balance ,Shares at Dec. 31, 2016			600,000
Net income	17,789						17,789
Redeemable convertible series B preferred stock dividends	(4,500)		$ (4,500)				(4,500)
Equity-based compensation	140					140
Ending Balance at Mar. 31, 2017	$ 207,565				$ 2	$ 108,555	$ 99,008
Ending Balance, Shares at Mar. 31, 2017				1,000,000	206,380,800
Preferred Stock Value, Ending Balance at Mar. 31, 2017			$ 502,213
Preferred Stock Ending Balance ,Shares at Mar. 31, 2017			600,000

[1] Balances derived from audited financial statements as of December 31, 2016.