CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net capitalized interest	$ 513	$ 460	$ 325
Common Stock
Company's common stock surrendered in exchange for the exercise of stock options (in shares)	0	14	185

The amount of cash paid during the current period for interest that is capitalized.

Reference 1: 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=66902209&loc=d3e3213-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration