Summary of Impact of Restatements on Each Affected Line of Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011
Prepaid expenses and other	$ 5,167	$ 5,416	$ 4,581	$ 4,357	$ 4,087	$ 4,740	$ 2,876	$ 1,930
Total assets	74,955	80,921	82,287	82,870	85,010	90,770	57,978	55,450
Deferred revenues	11,711	11,279	10,214	9,717	9,345	3,106	2,237	1,820
Total liabilities	36,068	35,992	39,754	38,248	35,837	32,602	28,086	27,578
Total liabilities and stockholders' equity	74,955	80,921	82,287	82,870	85,010	90,770	57,978	55,450
As Reported
Prepaid expenses and other	2,487	2,972	2,107	1,828	1,881	4,027	2,450	1,687
Total assets	72,275	78,477	79,813	80,341	82,804	90,057	57,552	55,207
Deferred revenues	9,031	8,835	7,740	7,188	7,139	2,393	1,811	1,577
Total liabilities	33,388	33,548	37,280	35,719	33,631	31,889	27,660	27,335
Total liabilities and stockholders' equity	72,275	78,477	79,813	80,341	82,804	90,057	57,552	55,207
Adjustments
Prepaid expenses and other	2,680	2,444	2,474	2,529	2,206	713	426	243
Total assets	2,680	2,444	2,474	2,529	2,206	713	426	243
Deferred revenues	2,680	2,444	2,474	2,529	2,206	713	426	243
Total liabilities	2,680	2,444	2,474	2,529	2,206	713	426	243
Total liabilities and stockholders' equity	$ 2,680	$ 2,444	$ 2,474	$ 2,529	$ 2,206	$ 713	$ 426	$ 243