Impairments Impairments Fair Value Nonrecurring (Details) (Fair Value, Measurements, Nonrecurring, USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Long-lived assets held for use
Property, Plant and Equipment [Line Items]
Assets, fair value	$ 65,203	$ 93,945	$ 14,801
Long-lived assets held for use | Level 1
Property, Plant and Equipment [Line Items]
Assets, fair value	0	0	0
Long-lived assets held for use | Level 2
Property, Plant and Equipment [Line Items]
Assets, fair value	0	0	0
Long-lived assets held for use | Level 3
Property, Plant and Equipment [Line Items]
Assets, fair value	65,203	93,945	14,801
Long-lived assets sold during the year
Property, Plant and Equipment [Line Items]
Assets, fair value	70,733		96,099
Long-lived assets sold during the year | Level 1
Property, Plant and Equipment [Line Items]
Assets, fair value	0		0
Long-lived assets sold during the year | Level 2
Property, Plant and Equipment [Line Items]
Assets, fair value	0		0
Long-lived assets sold during the year | Level 3
Property, Plant and Equipment [Line Items]
Assets, fair value	$ 70,733		$ 96,099