Statements of Consolidated Total Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred shares at par value	Common shares at par value Class A common shares at par value	Common shares at par value Class B common shares at par value	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income/(loss)	Common shares held by a subsidiary	Non-controlling interests
Balance at Dec. 31, 2009	$ 874,506	$ 0	$ 769	$ 181	$ 714,980	$ 196,802	$ (39,814)	$ (181)	$ 1,769
Increase (Decrease) in Stockholders' Equity
Issuance of class A common shares in public offering, net of issuance costs	248,052		253		247,799
Share based compensation	5,713				5,713
Share options exercised	1		1
Comprehensive loss:
Net losses on common shares	(62,580)					(62,759)			179
Other comprehensive income (loss)	1,203						1,229		(26)
Balance at Dec. 31, 2010	1,066,895	0	1,023	181	968,492	134,043	(38,585)	(181)	1,922
Increase (Decrease) in Stockholders' Equity
Issuance of class A common shares in public offering, net of issuance costs	(157)		0		(157)
Share based compensation	6,995				6,995
Share options exercised	3		3
Comprehensive loss:
Net losses on common shares	(87,596)					(87,780)			184
Other comprehensive income (loss)	(33,615)						(33,704)		89
Balance at Dec. 31, 2011	952,525	0	1,026	181	975,330	46,263	(72,289)	(181)	2,195
Increase (Decrease) in Stockholders' Equity
Share based compensation	6,776				6,776
Share options exercised	3		3
Comprehensive loss:
Net losses on common shares	(6,888)					(7,061)			173
Other comprehensive income (loss)	(14,093)						(14,092)		(1)
Balance at Dec. 31, 2012	$ 938,323	$ 0	$ 1,029	$ 181	$ 982,106	$ 39,202	$ (86,381)	$ (181)	$ 2,367