Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share Disclosure [Line Items]
Net income attributable to XO Group Inc.	$ 3,101	$ 2,059	$ 8,862	$ 5,593
Total weighted-average basic shares	24,686,000	24,285,000	24,591,000	24,762,000
Dilutive securities:
Total weighted-average diluted shares	25,879,000	24,818,000	25,579,000	25,328,000
Net income per share attributable to XO Group Inc. common stockholders:
Basic (usd per share)	$ 0.13	$ 0.08	$ 0.36	$ 0.23
Diluted (usd per share)	$ 0.12	$ 0.08	$ 0.35	$ 0.22
Weighted average number of antidilutive stock options and restricted stock excluded from the calculation of earnings per share (shares)	152,203	1,913	50,824	55,072
Restricted stock
Dilutive securities:
Dilutive securities (shares)	1,096,000	411,000	872,000	440,000
Employee Stock Purchase Plan
Dilutive securities:
Dilutive securities (shares)	8,000	7,000	9,000	9,000
Options
Dilutive securities:
Dilutive securities (shares)	89,000	115,000	107,000	117,000