Non-financial assets measured at fair value on a non-recurring basis (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of discontinued operations held for sale	$ 34,416,000	$ 57,040,000
Impairment of long-lived assets to be disposed of	7,031,000	3,166,000	65,144,000
Impairment of goodwill	0	2,055,000	11,907,000
Impairment of intangible assets		0	0
Impairment of other assets		1,299,000
Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of discontinued operations held for sale		22,040,000	63,522,000
Property, plant and equipment, fair value disclosure		3,521,000	6,000,000
Goodwill, fair value disclosure		7,515,000	0
Other assets, fair value disclosure		0
Level 1 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of discontinued operations held for sale		0	0
Property, plant and equipment, fair value disclosure		0	0
Goodwill, fair value disclosure		0	0
Other assets, fair value disclosure		0
Level 2 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of discontinued operations held for sale		0	0
Property, plant and equipment, fair value disclosure		0	0
Goodwill, fair value disclosure		0	0
Other assets, fair value disclosure		0
Level 3 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of discontinued operations held for sale		22,040,000	63,522,000
Property, plant and equipment, fair value disclosure		3,521,000	6,000,000
Goodwill, fair value disclosure		7,515,000	0
Other assets, fair value disclosure		0
Continuing operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill	0
Continuing operations | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	45,000,000
Continuing operations | Level 1 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	0
Continuing operations | Level 2 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	0
Continuing operations | Level 3 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	45,000,000
Discontinued operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill	3,187,000
Impairment of intangible assets	2,815,000
Discontinued operations | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	0
Goodwill, fair value disclosure	0
Finite-lived intangible assets, fair value disclosure	0
Discontinued operations | Level 1 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	0
Goodwill, fair value disclosure	0
Finite-lived intangible assets, fair value disclosure	0
Discontinued operations | Level 2 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	0
Goodwill, fair value disclosure	0
Finite-lived intangible assets, fair value disclosure	0
Discontinued operations | Level 3 | Fair value measurements, non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, fair value disclosure	0
Goodwill, fair value disclosure	0
Finite-lived intangible assets, fair value disclosure	0
Property, plant and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of property, plant and equipment		2,538,000	8,153,000
Property, plant and equipment | Continuing operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of property, plant and equipment	36,430,000
Property, plant and equipment | Discontinued operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of long-lived assets to be disposed of	$ 1,029,000