Expected Expiration Dates of Tax Loss CarryForwards (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Expiration Dates [Line Items]
Tax Benefit	$ 29,045	$ 26,952
Valuation Allowance	(6,335)	(11,760)
Net Tax Benefit	22,710	15,192
2012
Expiration Dates [Line Items]
Tax Benefit		205
Valuation Allowance		(205)
2013
Expiration Dates [Line Items]
Tax Benefit	247	277
Valuation Allowance	(247)	(242)
Net Tax Benefit		35
2014
Expiration Dates [Line Items]
Tax Benefit	176	215
Valuation Allowance	(176)	(215)
2015
Expiration Dates [Line Items]
Tax Benefit	353	391
Valuation Allowance	(106)	(112)
Net Tax Benefit	247	279
2016
Expiration Dates [Line Items]
Tax Benefit	98	344
Valuation Allowance	(68)	(116)
Net Tax Benefit	30	228
2017
Expiration Dates [Line Items]
Tax Benefit	231
Valuation Allowance	(212)
Net Tax Benefit	19
2018
Expiration Dates [Line Items]
Tax Benefit	16	41
Net Tax Benefit	16	41
2019
Expiration Dates [Line Items]
Tax Benefit	119	124
Valuation Allowance	(2)
Net Tax Benefit	117	124
2020
Expiration Dates [Line Items]
Tax Benefit	24
Valuation Allowance	(9)
Net Tax Benefit	15
2021
Expiration Dates [Line Items]
Tax Benefit	25
Net Tax Benefit	25
2022
Expiration Dates [Line Items]
Tax Benefit	70
Valuation Allowance	(12)
Net Tax Benefit	58
2023
Expiration Dates [Line Items]
Tax Benefit		505
Net Tax Benefit		505
2024
Expiration Dates [Line Items]
Tax Benefit		674
Net Tax Benefit		674
2026
Expiration Dates [Line Items]
Tax Benefit	554
Net Tax Benefit	554
2027
Expiration Dates [Line Items]
Tax Benefit	686	265
Net Tax Benefit	686	265
2028
Expiration Dates [Line Items]
Tax Benefit		147
Net Tax Benefit		147
2029
Expiration Dates [Line Items]
Tax Benefit		213
Net Tax Benefit		213
2030
Expiration Dates [Line Items]
Tax Benefit	43
Net Tax Benefit	43
2032
Expiration Dates [Line Items]
Tax Benefit	299
Valuation Allowance	(265)
Net Tax Benefit	34
Indefinite Life
Expiration Dates [Line Items]
Tax Benefit	26,104	23,551
Valuation Allowance	(5,238)	(10,870)
Net Tax Benefit	$ 20,866	$ 12,681