XML 51 R41.htm IDEA: XBRL DOCUMENT v3.10.0.1

Business Segments - Narratives (Details)	Dec. 31, 2017
Segment Reporting [Abstract]
Monthly allocation of corporate expenses	1.00%

X

- References

No definition available.

+ Details

Name:	fstr_MonthlyAllocationCorporateOperatingExpense
Namespace Prefix:	fstr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	us-gaap_SegmentReportingAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration