Significant Accounting Policies Supplemental Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Income taxes, cash paid (received)	$ 35us-gaap_IncomeTaxesPaidNet	$ 50us-gaap_IncomeTaxesPaidNet	$ 2,944us-gaap_IncomeTaxesPaidNet
Interest, cash paid (received)	63,482us-gaap_InterestPaid	57,789us-gaap_InterestPaid	51,271us-gaap_InterestPaid
Capital expenditures included in trade accounts payable	$ 8,555	$ 12,025	$ 13,136

Future cash outflow to pay for purchases of fixed assets that have occurred.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

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Period Type:	duration