Employee Benefit Plans - Fair Values of Pension Plan Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets	$ 1,443	$ 30,453	$ 29,231
Cash and cash equivalents [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		66
Fixed income [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		21,438
Mutual fund [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		5,399
Insurance contracts [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets	1,443	3,550
Level 1 [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		66
Level 1 [Member] | Cash and cash equivalents [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		66
Level 1 [Member] | Fixed income [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 1 [Member] | Mutual fund [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 1 [Member] | Insurance contracts [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 2 [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets	1,443	30,387
Level 2 [Member] | Cash and cash equivalents [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 2 [Member] | Fixed income [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		21,438
Level 2 [Member] | Mutual fund [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets		5,399
Level 2 [Member] | Insurance contracts [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets	1,443	3,550
Level 3 [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 3 [Member] | Cash and cash equivalents [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 3 [Member] | Fixed income [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 3 [Member] | Mutual fund [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets
Level 3 [Member] | Insurance contracts [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Fair values of pension plan assets