Equity-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Granted
Unearned compensation costs related to awards granted	$ 18,534,000
Unearned compensation cost, expected to be recognized over period (years)	2 years 4 months 24 days
Expected weighted-average life	5 years 5 months 23 days	5 years 5 months 1 day	5 years 4 months 10 days
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period (in years)	10 years
Shares expected to vest	20,155
Stock Appreciation Rights (SARs) [Member] | Vest After One Year [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares expected to vest		16,045
Stock Appreciation Rights (SARs) [Member] | Vest Annually In Each Of First Four Anniversaries [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares expected to vest	410,885	371,802
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected weighted-average life	3 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected weighted-average life	1 year
Stock Option And Stock Appreciation Rights (SARs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Stock Option And Stock Appreciation Rights (SARs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		5 years
2011 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance of awards	5,500,000
Shares available for grant	4,805,599
Options outstanding	438,671
Expiration period (in years)		10 years
2002 Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period (in years)	10 years
Shares outstanding and exercisable	80,000
2001 Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum working hours per week		20
Maximum percentage of compensation deductions		10.00%
Stock purchase plan expense	$ 242,000	321,000	315,000
2001 Stock Purchase Plan [Member] | Date Of The Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of purchase price on fair market value		95.00%
2001 Stock Purchase Plan [Member] | Date Of Purchase [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of purchase price on fair market value		95.00%
RSA [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
RSA [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	5 years
2006 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period (in years)	10 years
Expiration period, if employee is terminated involuntarily other than for cause (days)	90
Expiration period, if employee voluntarily terminates his or her employment (days)	30
Expiration period, if employee's employment terminates due to death, disability, or retirement (Years)	1
Shares outstanding and exercisable	1,830,544
1997 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding and exercisable	705,445
WhereNet Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding and exercisable	12,988