Assets Manufactured for Internal Use, net - Useful Life (Details) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended			27 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Change in estimate of useful life of assets manufactured for internal use
Profit before tax										$ 15,205	$ (10,167)	$ (16,104)
Net income (loss)	$ 826	$ 6,101	$ 5,883	$ 1,868	$ 164	$ (4,704)	$ (6,900)	$ 174		$ 14,678	(11,266)	(17,144)
Assets Manufactured for Internal Use | Useful life of assets manufactured for internal use | Adjustment
Change in estimate of useful life of assets manufactured for internal use
Useful life									5 years				10 years
Profit before tax											300	100
Net income (loss)											$ 300	$ 100