Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Commitments and Contingencies - Letters of Credit and Guarantees (Details) - USD ($)	Jun. 30, 2017	Apr. 28, 2017	Dec. 31, 2016
Financial Guarantee
Loss contingencies
Letters of credit outstanding	$ 34,400,000		$ 28,700,000
Uncommitted Letter of Credit and Reimbursement Agreement \| Letter of Credit
Loss contingencies
Maximum borrowing capacity		$ 30,000,000.0