Stock Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		398 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		1 Months Ended			9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		1 Months Ended	9 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013 Minimum	Sep. 30, 2012 Minimum	Sep. 30, 2013 Minimum	Sep. 30, 2012 Minimum	Sep. 30, 2013 Maximum	Sep. 30, 2012 Maximum	Sep. 30, 2013 Maximum	Sep. 30, 2012 Maximum	Aug. 31, 2013 Restricted Stock Awards (RSA)	Jun. 30, 2013 Restricted Stock Awards (RSA)	Apr. 30, 2012 Restricted Stock Awards (RSA)	Sep. 30, 2013 Restricted Stock Awards (RSA)	Sep. 30, 2013 Employee Stock Purchase Plan	Sep. 30, 2013 Employee Stock Purchase Plan	Sep. 30, 2013 Employee Stock Purchase Plan Minimum	Sep. 30, 2013 Employee Stock Purchase Plan Minimum	Sep. 30, 2013 Employee Stock Purchase Plan Maximum	Jun. 30, 2013 Performance	Sep. 30, 2013 Stock Incentive, 2002 to December 2010	Sep. 30, 2013 Stock Incentive Plan, 2011, Beginning in June 2011	Sep. 30, 2013 Stock Incentive Plan, 2011, Beginning in June 2011 Employee Stock Purchase Plan	Sep. 30, 2013 Stock Incentive Plan, 2011, Beginning in June 2011 First Anniversary	Sep. 30, 2013 Stock Incentive Plan, 2011, Beginning in June 2011 Vesting Month After First Anniversary	Sep. 30, 2013 Amended and Restated 2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock remain available for future grant under the 2011 Plan																									2,950,714
Shares available to be issued under the ESPP																		250,000	250,000							250,000
Additional shares available for grant																													3,600,000
Share based compensation granted under plan vest period																								3 years	4 years
Underlying shares vesting on anniversary of grant																								33.33%			25.00%	2.50%
Term of award																								10 years
Stock options granted			2,063,396																				459,500
Weighted-average fair value per share of stock-based awards, granted to employees	$ 26.92	$ 7.09	$ 23.25	$ 6.52
Intrinsic value of stock options exercised			$ 5,100,000	$ 1,000,000
Grant date fair value of stock options that vested			3,000,000	3,200,000
Granted shares														7,500	6,000	32,377	6,000
Grant date fair value of shares grant															$ 34.92		$ 34.92
Percentage of closing price of common stock																			85.00%
Shares estimated to be issued under the ESPP																			59,563
Weighted average fair value stock purchase																				$ 16.12		$ 24.65
Weighted- average stock-price volatility						80.00%	79.70%	80.00%	79.70%	88.90%	94.80%	88.90%	94.80%								84.00%	98.00%
Risk-free interest rate						0.70%	0.60%	0.70%	0.60%	1.40%	1.10%	1.40%	1.10%								0.10%	0.40%
Expected lives						4 years 10 months 24 days	5 years 1 month 6 days	4 years 10 months 24 days	5 years 1 month 6 days	5 years	5 years 3 months 18 days	5 years	5 years 3 months 18 days								8 months 12 days	2 years 2 months 12 days
Stock-based compensation			7,476,000	1,840,000	39,549,000													300,000	300,000
Unrecognized compensation cost related to non-vested share-based compensation arrangements granted, including stock options and restricted stock	$ 49,600,000		$ 49,600,000		$ 49,600,000
Unrecognized compensation costs expected to be recognized period			3 years 2 months 12 days