Stockholders' Equity - Stock Options Outstanding and Exercisable (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012
Non-Qualified Stock Option Plans [Member] | $7.86 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 7.86
Stock Options Outstanding, Shares Outstanding	33,050
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	5 years 11 months 1 day
Stock Options Outstanding, Weighted-Average Exercise Price	$ 7.86
Stock Options, Intrinsic Value of Shares Outstanding	$ 911,000
Stock Options Exercisable, Shares Exercisable	19,450
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	5 years 11 months 1 day
Stock Options Exercisable, Weighted-Average Exercise Price	$ 7.86
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	536,000
Non-Qualified Stock Option Plans [Member] | $8.01 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 8.01
Stock Options Outstanding, Shares Outstanding	220,000
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	3 years 9 months
Stock Options Outstanding, Weighted-Average Exercise Price	$ 8.01
Stock Options, Intrinsic Value of Shares Outstanding	6,030,000
Stock Options Exercisable, Shares Exercisable	40,000
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	3 years 9 months
Stock Options Exercisable, Weighted-Average Exercise Price	$ 8.01
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	1,096,000
Non-Qualified Stock Option Plans [Member] | $34.50 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 34.50
Stock Options Outstanding, Shares Outstanding	5,000
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	8 years 11 months 1 day
Stock Options Outstanding, Weighted-Average Exercise Price	$ 34.50
Stock Options, Intrinsic Value of Shares Outstanding	5,000
Stock Options Exercisable, Shares Exercisable	825
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	8 years 11 months 1 day
Stock Options Exercisable, Weighted-Average Exercise Price	$ 34.50
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	1,000
Non-Qualified Stock Option Plans [Member] | $7.86 - $34.50 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 7.86
Exercise prices, upper range	$ 34.5
Stock Options Outstanding, Shares Outstanding	258,050
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	4 years 1 month 17 days
Stock Options Outstanding, Weighted-Average Exercise Price	$ 8.50
Stock Options, Intrinsic Value of Shares Outstanding	6,946,000
Stock Options Exercisable, Shares Exercisable	60,275
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	4 years 6 months 7 days
Stock Options Exercisable, Weighted-Average Exercise Price	$ 8.32
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	1,633,000
Qualified Stock Option Plans [Member] | $5.10 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 5.10
Stock Options Outstanding, Shares Outstanding	11,000
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	2 years 11 months 1 day
Stock Options Outstanding, Weighted-Average Exercise Price	$ 5.10
Stock Options, Intrinsic Value of Shares Outstanding	333,000
Stock Options Exercisable, Shares Exercisable	11,000
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	2 years 11 months 1 day
Stock Options Exercisable, Weighted-Average Exercise Price	$ 5.10
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	333,000
Qualified Stock Option Plans [Member] | $7.86 - $8.17 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 7.86
Exercise prices, upper range	$ 8.17
Stock Options Outstanding, Shares Outstanding	42,085
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	5 years 11 months 1 day
Stock Options Outstanding, Weighted-Average Exercise Price	$ 7.87
Stock Options, Intrinsic Value of Shares Outstanding	1,160,000
Stock Options Exercisable, Shares Exercisable	19,305
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	5 years 11 months 1 day
Stock Options Exercisable, Weighted-Average Exercise Price	$ 7.87
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	532,000
Qualified Stock Option Plans [Member] | $9.69 - $9.97 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 9.69
Exercise prices, upper range	$ 9.97
Stock Options Outstanding, Shares Outstanding	176,830
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	5 years 9 months 29 days
Stock Options Outstanding, Weighted-Average Exercise Price	$ 9.69
Stock Options, Intrinsic Value of Shares Outstanding	4,549,000
Stock Options Exercisable, Shares Exercisable	82,650
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	5 years 9 months 29 days
Stock Options Exercisable, Weighted-Average Exercise Price	$ 9.69
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	2,126,000
Qualified Stock Option Plans [Member] | $29.99 - $34.50 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 29.99
Exercise prices, upper range	$ 34.5
Stock Options Outstanding, Shares Outstanding	249,000
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	8 years 10 months 24 days
Stock Options Outstanding, Weighted-Average Exercise Price	$ 34.41
Stock Options, Intrinsic Value of Shares Outstanding	252,000
Stock Options Exercisable, Shares Exercisable	41,085
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	8 years 10 months 24 days
Stock Options Exercisable, Weighted-Average Exercise Price	$ 34.41
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	42,000
Qualified Stock Option Plans [Member] | $5.10 - $34.50 [Member]
Stockholders Equity [Line Items]
Exercise prices, lower range	$ 5.1
Exercise prices, upper range	$ 34.5
Stock Options Outstanding, Shares Outstanding	478,915
Stock Options Outstanding, Weighted-Average Remaining Contractual Life in Years	7 years 4 months 13 days
Stock Options Outstanding, Weighted-Average Exercise Price	$ 22.28
Stock Options, Intrinsic Value of Shares Outstanding	6,294,000
Stock Options Exercisable, Shares Exercisable	154,040
Stock Options Exercisable, Weighted-Average Remaining Contractual Life in Years	6 years 5 months 12 days
Stock Options Exercisable, Weighted-Average Exercise Price	$ 15.73
Stock Options Exercisable, Intrinsic Value of Shares Outstanding	$ 3,033,000