Supplemental Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2018

Supplemental Cash Flow Elements [Abstract]

Summary of Supplemental Cash Flow Information

The following additional information is provided with respect to the condensed consolidated statements of cash flows (in thousands):

	Three Months Ended March 31,
	2018		2017
Noncash Investing and Financing Activities:
Transfers from inventory to field equipment	$	4,187	$	5,903
Transfers from field equipment to deferred cost of revenues	3,423		2,313
Market value of shares received in payment for exercise of stock options	674		2,295
PP&E financed by construction liability	58		109