Earnings Per Share Information (Computation Of Basic And Diluted Income Per Share) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Computation of basic income per share attributable to CBRE Group, Inc. shareholders:
Net income attributable to CBRE Group, Inc. shareholders	$ 172,998		$ 39,709		$ 75,873		$ 26,975		$ 79,763		$ 63,807		$ 61,223		$ 34,369		$ 315,555	$ 239,162	$ 200,345
Weighted average shares outstanding for basic income per share	325,372,928	[1]	322,331,850	[1]	320,852,344	[1]	320,671,395	[1]	320,638,316	[1]	318,867,447	[1]	317,698,275	[1]	316,563,392	[1]	322,315,576	318,454,191	313,873,439
Basic income per share attributable to CBRE Group, Inc. shareholders	$ 0.53	[1]	$ 0.12	[1]	$ 0.24	[1]	$ 0.08	[1]	$ 0.25	[1]	$ 0.20	[1]	$ 0.19	[1]	$ 0.11	[1]	$ 0.98	$ 0.75	$ 0.64
Computation of diluted income per share attributable to CBRE Group, Inc. shareholders:
Net income attributable to CBRE Group, Inc. shareholders	$ 172,998		$ 39,709		$ 75,873		$ 26,975		$ 79,763		$ 63,807		$ 61,223		$ 34,369		$ 315,555	$ 239,162	$ 200,345
Weighted average shares outstanding for basic income per share	325,372,928	[1]	322,331,850	[1]	320,852,344	[1]	320,671,395	[1]	320,638,316	[1]	318,867,447	[1]	317,698,275	[1]	316,563,392	[1]	322,315,576	318,454,191	313,873,439
Dilutive effect of contingently issuable shares																	3,082,173	3,160,702	2,530,103
Dilutive effect of stock options																	1,646,396	2,108,862	2,613,345
Weighted average shares outstanding for diluted income per share	329,012,910	[1]	327,309,341	[1]	326,081,681	[1]	325,738,859	[1]	324,117,111	[1]	323,714,703	[1]	324,093,042	[1]	322,920,829	[1]	327,044,145	323,723,755	319,016,887
Diluted income per share attributable to CBRE Group, Inc. shareholders	$ 0.53	[1]	$ 0.12	[1]	$ 0.23	[1]	$ 0.08	[1]	$ 0.25	[1]	$ 0.20	[1]	$ 0.19	[1]	$ 0.11	[1]	$ 0.97	$ 0.74	$ 0.63

[1] EPS is defined as earnings per share.