Accrued Liabilities Accrued Liabilities Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Accrued Liabilities, Current [Abstract]
Refundable deposits, contracted	$ 240
Refundable deposits, proceeds	$ 160

Amount of cash inflow from customers for revenue related transactions that are refundable to the customers and do not meet the criteria for revenue recognition.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.4(a))
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Name:	us-gaap_CustomerRefundableFeesProceeds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration