Earnings per Share - Computation of Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income (loss) (numerator):
Net (loss) income	$ (3,753)	$ (8,398)	$ 1,275	$ (16,663)
Noncontrolling interest	(761)	3,730	3,075	7,686
Dividends on preferred shares	7,412	5,569	12,981	11,138
Net loss attributable to common shareholders	$ (10,404)	$ (17,697)	$ (14,781)	$ (35,487)
Weighted-average shares (denominator) (in shares)	238,481,265	211,487,164	228,819,566	211,484,461
Net loss per share-basic and diluted:
Net loss per share-basic and diluted (in USD per share)	$ (0.04)	$ (0.08)	$ (0.06)	$ (0.17)