Employee Benefit Plans - Composition of Pension Plan Assets by Fair Value Level (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Total	$ 31,937	$ 33,573
U.K. plan
Defined Benefit Plan Disclosure [Line Items]
Total	10,331	10,494
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Total	42,268	44,067	$ 48,816
CMRT | U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Total	31,937	33,573
Other | U.K. plan
Defined Benefit Plan Disclosure [Line Items]
Total	10,331	10,494
Level 1 | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Total	10,331	10,494
Level 1 | Other | U.K. plan
Defined Benefit Plan Disclosure [Line Items]
Total	10,331	10,494
Level 2 | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Total	31,937	33,573
Level 2 | CMRT | U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Total	$ 31,937	$ 33,573