General - General information (Details) - USD ($)	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015
General
Decrease in other adjustments to reconcile net margin to net cash provided by operating activities	$ (4,424,000)	$ (5,076,000)
Decrease in cash paid for property additions	$ (421,384,000)	(335,217,000)
Adjustments
General
Decrease in other adjustments to reconcile net margin to net cash provided by operating activities		26,116,000
Decrease in cash paid for property additions		$ 26,116,000

The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3213-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration