Acquisitions - Additional Information (Detail)	12 Months Ended					12 Months Ended				12 Months Ended
	Dec. 31, 2013 Senn Delaney [Member] USD ($)	Dec. 31, 2012 Senn Delaney [Member] USD ($)	Dec. 31, 2011 Senn Delaney [Member] USD ($)	Dec. 31, 2013 Scambler MacGregor [Member] USD ($)	Nov. 30, 2013 Scambler MacGregor [Member] AUD	Dec. 31, 2013 Bell McCaw Bampflyde Limited [Member] USD ($)	Dec. 31, 2012 Bell McCaw Bampflyde Limited [Member] USD ($)	Dec. 31, 2011 Bell McCaw Bampflyde Limited [Member] USD ($)	Mar. 31, 2010 Bell McCaw Bampflyde Limited [Member] NZD	Dec. 31, 2013 Iron Hill [Member] USD ($)	Dec. 31, 2011 Iron Hill [Member] USD ($)	Dec. 31, 2010 Iron Hill [Member] USD ($)	Dec. 31, 2009 Iron Hill [Member] USD ($)
Business Acquisition [Line Items]
Acquisition Date	December 2013			November 2013		March 2010				May 2008
Consideration paid to purchase		$ 53,500,000		$ 1,000,000	1,100,000	$ 700,000			800,000
Estimated fair value of future earnout payments associated with acquisition					2,800,000	1,200,000			1,400,000	0
Earnout payments accrued				2,000,000	2,200,000
Additional payments relates to final working capital settlement				100,000
Identifiable intangible assets				400,000		0
Goodwill acquired		29,707,000		2,729,000
Percentage of equity of acquired company		100.00%
Additional cash consideration	15,000,000
Specific earnings milestones achieved period	2 years
General and administrative expense of acquisition related costs	2,100,000
Retention escrow paid	6,500,000	6,500,000
Minimum service period acquired to cover under plan	3 years
Compensation expense	2,300,000	2,300,000	2,300,000
Earnout payments for acquisitions						400,000	400,000	400,000			3,900,000
Purchase price allocation for Goodwill						1,600,000			2,000,000
Purchase price allocation for property and equipment						100,000			200,000
Earnout payment to be received											$ 4,400,000	$ 4,400,000	$ 4,400,000