Purchase Price of Acquisition (Detail) (Thomas Plant, USD $) In Thousands, unless otherwise specified	0 Months Ended
	Jan. 15, 2014
Thomas Plant
Business Acquisition [Line Items]
Cash	$ 61,302
Share consideration issued	8,382	[1]
Value of contingent consideration	2,488	[2]
Working capital adjustment	374	[3]
Total purchase price	$ 72,546

[1] Share consideration issued is valued at the closing market price discounted to account for lack of marketability related to the lock up period as described in the share purchase agreement.

[2] The value of contingent consideration represents the present value of the estimated payments related to the attainment of certain financial targets for the years 2014 through 2016. The maximum undiscounted contingent consideration to be paid on the agreement is £5.5 million ($9.0 million).

[3] A working capital adjustment was made in May 2014 as provided for in the share purchase agreement.