Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share Disclosure [Line Items]
Net income attributable to XO Group Inc.	$ 4,088	$ 3,138	$ 5,761	$ 3,535
Total weighted-average basic shares	24,621,000	24,488,000	24,541,000	25,004,000
Dilutive securities:
Total weighted-average diluted shares	25,594,000	25,078,000	25,426,000	25,585,000
Net income per share attributable to XO Group Inc. common stockholders:
Basic (usd per share)	$ 0.17	$ 0.13	$ 0.23	$ 0.14
Diluted (usd per share)	$ 0.16	$ 0.13	$ 0.23	$ 0.14
Weighted average number of antidilutive stock options and restricted stock excluded from the calculation of earnings per share (shares)	134	275	268	81,527
Restricted stock
Dilutive securities:
Dilutive securities (shares)	855,000	456,000	760,000	453,000
Employee Stock Purchase Plan
Dilutive securities:
Dilutive securities (shares)	9,000	12,000	9,000	10,000
Options
Dilutive securities:
Dilutive securities (shares)	109,000	122,000	116,000	118,000