Retirement Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum percentage of eligible compensation participants may contribute (up to 50%) (percent)	50.00%
Greenhill & Co., LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Incurred costs for contributions to retirement plan	$ 200,000	$ 300,000	$ 300,000
Contributions due to Retirement Plan included in compensation payable	200,000	100,000
Greenhill And Company International LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Costs incurred for pension	600,000	700,000	600,000
Contributions due to Retirement Plan included in compensation payable	0	0
Greenhill & Co. Australia Pty Limited
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Costs incurred for pension	500,000	600,000	600,000
Contributions due to Retirement Plan included in compensation payable	0	0
Greenhill & Co. Australia Pty Limited | Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of compulsory contribution for superannuation on employees gross earnings (percent)	9.00%
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company's maximum matching contributions per employee (up to $1,000)	$ 1,000