Selected Quarterly Financial Data (Details) (USD $) In Thousands, except Share data, unless otherwise specified	2 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 2,000	$ 41,417	$ 29,611	$ 37,620	$ 33,268	$ 47,405	$ 33,848	$ 42,198	$ 37,224	$ 141,916	$ 160,675	$ 197,627
Operating income/(loss)		6,964	(14,850)	2,244	(2,190)	5,860	(4,076)	(636)	(3,045)	(7,832)	(1,897)	(56,396)
Net (loss)/income		$ 6,843	$ (11,065)	$ 1,767	$ (2,603)	$ 6,976	$ (4,295)	$ (1,180)	$ (3,273)	$ (5,058)	$ (1,772)	$ (56,085)
(Loss)/earnings per share - basic and diluted		$ 0.12	$ (0.19)	$ 0.03	$ (0.05)	$ 0.12	$ (0.06)	$ (0.02)	$ (0.05)	$ (0.09)	$ (0.03)	$ (0.83)
Weighted average common shares outstanding, Basic		57,090,226	57,074,872	56,964,079	56,680,826	57,630,635	67,490,820	67,371,869	67,241,626	56,953,958	64,912,368
Weighted average common shares outstanding, Diluted		57,875,017	57,074,872	57,729,551	56,680,826	58,011,641	67,490,820	67,371,869	67,241,626	56,953,958	64,912,368