Statements of Condensed 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, 2012	$ 938,323	$ 0	$ 1,029	$ 181	$ 982,106	$ 39,202	$ (86,381)	$ (181)	$ 2,367
Increase (Decrease) in Stockholders' Equity
Share-based compensation	1,550				1,550
Exercised stock options and vested share awards	1		1
Comprehensive loss:
Net losses attributable to common shares	(47,006)					(47,215)			209
Other comprehensive loss	(15,361)						(15,367)		6
Balance at Mar. 31, 2013	877,507	0	1,030	181	983,656	(8,013)	(101,748)	(181)	2,582
Balance at Dec. 31, 2013	910,645	0	1,036	181	992,860	7,643	(93,317)	(181)	2,423
Increase (Decrease) in Stockholders' Equity
Share-based compensation	887				887
Exercised stock options and vested share awards	1		1
Comprehensive loss:
Net losses attributable to common shares	(20,644)					(20,760)			116
Other comprehensive loss	(49,472)						(48,594)		(878)
Balance at Mar. 31, 2014	$ 841,417	$ 0	$ 1,037	$ 181	$ 993,747	$ (13,117)	$ (141,911)	$ (181)	$ 1,661