Employee Benefit Plans - Composition of Pension Plan Assets by Fair Value Level (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total	$ 48,816	$ 49,402
CMRT | U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Total	38,131	39,230
Other | U.K. plan
Defined Benefit Plan Disclosure [Line Items]
Total	10,685	10,172
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total	10,685	10,172
Level 1 | Other | U.K. plan
Defined Benefit Plan Disclosure [Line Items]
Total	10,685	10,172
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total	38,131	39,230
Level 2 | CMRT | U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Total	$ 38,131	$ 39,230