Stock-Based Compensation - Additional Information (Detail) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended		1 Months Ended			6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended		1 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended				1 Months Ended	6 Months Ended
	Mar. 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Feb. 28, 2013 Employee Stock Purchase Plan ("ESPP") [Member]	Feb. 29, 2012 Employee Stock Purchase Plan ("ESPP") [Member]	May 31, 1998 Employee Stock Purchase Plan ("ESPP") [Member]	Jun. 30, 2013 Employee Stock Purchase Plan ("ESPP") [Member]	Dec. 31, 2012 Employee Stock Purchase Plan ("ESPP") [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jul. 31, 2010 Stock Plans [Member]	Jun. 30, 2013 Stock Plans [Member]	Jun. 30, 2012 Stock Plans [Member]	Jun. 30, 2013 Stock Plans [Member]	Jun. 30, 2012 Stock Plans [Member]	Jun. 30, 2013 Service Based Restricted Stock Units [Member]	Jun. 30, 2012 Service Based Restricted Stock Units [Member]	Jun. 30, 2013 Service Based Restricted Stock Units [Member]	Jun. 30, 2012 Service Based Restricted Stock Units [Member]	Jun. 30, 2013 Performance Units [Member]	Jun. 30, 2013 Performance Units [Member]	Jun. 30, 2012 Performance Units [Member]	Jun. 30, 2013 Time Based Restricted Stock Units [Member]	Jun. 30, 2013 Time Based Restricted Stock Units [Member]	Jun. 30, 2012 Time Based Restricted Stock Units [Member]	Jun. 30, 2013 Restricted Stock Units [Member]	Jun. 30, 2013 Restricted Stock Units [Member]	Jun. 30, 2012 Restricted Stock Units [Member]	Jun. 30, 2013 Employee Withholding Taxes on Stock Awards [Member]	Jun. 30, 2012 Employee Withholding Taxes on Stock Awards [Member]	Apr. 30, 2013 Retention Stock Options [Member] Executive Officer [Member]	Jun. 30, 2013 Retention Stock Options [Member] Executive Officer [Member]	Jun. 30, 2013 Retention Stock Options [Member] Minimum [Member] Executive Officer [Member]	Jun. 30, 2013 Retention Stock Options [Member] Maximum [Member] Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based expense		$ 1,100,000	$ 900,000	$ 1,700,000	$ 1,600,000						$ 800,000	$ 800,000	$ 1,300,000	$ 1,500,000
Compensation expense for share-based payments		1,098,000	943,000	1,722,000	1,640,000											300,000	100,000	400,000	100,000
Grants vesting period													4 years									4 years															2 years	4 years
Restricted stock awards issued													13,402							13,402		13,402	229,950				0	0	5,000
Fair value of options issued																				100,000		100,000	1,600,000						35,000
Restricted stock awards cancellation													9,361							6,861	46,668	9,361	52,656	147,250	147,250	11,320	1,125	1,125			1,125
Grant date fair value of restricted stock cancelled																				45,000	300,000	62,000	400,000	1,000,000	1,000,000	79,000	8,000	8,000		25,000	25,000
Shares, other than options, vested													352,565							13,012	14,025	352,565	466,255			4,836				3,850	3,850	2,600
Grant date fair value of restricted stock vested																				100,000	100,000	2,000,000	2,700,000
Restricted shares vested grant date intrinsic value																				100,000	100,000	2,600,000	3,500,000			36,000				28,000	28,000	20,000
Unrecognized compensation expense											1,900,000		1,900,000			2,400,000		2,400,000												29,000	29,000
Weighted average period													1 year 4 months 24 days					1 year 7 months 6 days													1 year 6 months
Percent of options vested																		25.00%
Employee stock options vesting provisions, description																		25% vest one year from the date of grant and thereafter in monthly increments over the remaining three years.
Options vested in remaining period																		3 years
Period of termination of employment																		90 days
Stock options granted period															7 years			10 years
Options granted				689,550												688,050	4,500	689,550	4,500							169,650									182,500	182,500
Weighted average exercise price granted																2,880,000		2,880,000
Proceeds from options exercised																13,000	25,000	91,000	25,000
Option exercised				11,841												1,647	3,719	11,841	3,719
Intrinsic value																3,000	3,000	7,000	3,000
Shares expired				88,568												19,664	96,802	111,201	216,350
Weighted average exercise price granted																	$ 2.77		$ 2.77
Lower range of exercise prices				$ 5.50
Upper range of exercise prices				$ 11.84
Intrinsic value based on share price		$ 8.48		$ 8.48
Weighted average grant date fair value																																			$ 2.83
Grant date fair value of options granted																										1,200,000
Grant date fair value of restricted stock vested																										33,000						16,000
Performance share units converted to restricted stock awards																										139,150
Percentage of fair market value to determine purchase price								85.00%
Offering period										6 months
Proceeds of from issuance of shares under ESPP						300,000	300,000
Options issued						61,230	48,032
Rate of discount on fair market value of common stock under ESPP									15.00%
Period of expected life, options granted									5 years
Payment of withholding taxes related to stock awards																																	900,000	1,200,000
Repurchase of shares		59,510
Repurchase of shares, Amount	5,000,000			435,000
Average price of repurchased share		$ 7.31
Repurchase of shares, outstanding amount		$ 4,600,000