Deferred tax reconciliation (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Change in net deferred income tax liability from the preceding table	$ 3,497
Deferred taxes associated with other comprehensive loss	1,267
Deferred taxes associated with discontinued operations	(9,863)
Other	(2,404)
Deferred income tax expense for the period	$ (7,503)	$ 118,925	$ 66,585