Income Taxes - Net Operating Loss Carryforwards for Tax Purposes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
Amounts	$ 78,429
Stock Option Adjustments	4,777
Total	83,206
Expiration Dates 2023 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	1,523
Total	1,523
Expiration Dates	2023
Expiration Dates 2024 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	1,082
Total	1,082
Expiration Dates	2024
Expiration Dates 2025 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	2,594
Total	2,594
Expiration Dates	2025
Expiration Dates 2026 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	1,683
Total	1,683
Expiration Dates	2026
Expiration Dates 2027 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	1,020
Total	1,020
Expiration Dates	2027
Expiration Dates 2028 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	1,308
Total	1,308
Expiration Dates	2028
Expiration Dates 2029 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	3,299
Total	3,299
Expiration Dates	2029
Expiration Dates 2030 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	12,605
Stock Option Adjustments	750
Total	13,355
Expiration Dates	2030
Expiration Dates 2031 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	18,642
Stock Option Adjustments	2,984
Total	21,626
Expiration Dates	2031
Expiration Date 2032 [Member]
Operating Loss Carryforwards [Line Items]
Amounts	34,673
Stock Option Adjustments	1,043
Total	$ 35,716
Expiration Dates	2032