Enterprise-Wide Disclosures (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas

Financial Information About Geographic Areas	2017		2016		2015
(amounts in thousands)
Revenue from External Customers:
United States	$	219,886	$	253,955	$	301,826
Belgium (1)		39,347		35,995		35,931
Luxembourg (1)		36,954		31,441		28,562
Other European country		4,824		3,193		2,814
Other country		199		309		345
Total foreign revenue		81,324		70,938		67,652
Total revenue	$	301,210	$	324,893	$	369,478
Long-lived Assets:
United States	$	5,206	$	4,280	$	4,208
United Kingdom (2)		1,005		792		461
Other European countries		782		791		819
Other Country		3		—		—
Total long-lived assets	$	6,996	$	5,863	$	5,488
Deferred Tax Assets, Net of Valuation Allowance:
United States	$	3,810	$	6,886	$	6,352
Europe		51		—		54
Total deferred tax assets, net	$	3,861	$	6,886	$	6,406

(1) Revenue for our Belgium and Luxembourg operations has been disclosed separately as it exceeds 10% of consolidated revenue in at least one of the years presented.

(2) Long-lived assets for our United Kingdom operations has been disclosed separately as it exceeds 10% of consolidated long-lived assets in at least one of the years presented.