Share-Based Compensation Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended						12 Months Ended
	Dec. 31, 2013 Age	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Incentive Plan [Member]	Sep. 27, 2008 Incentive Plan [Member]	Dec. 31, 2013 Employee Stock Purchase Plan [Member]	Dec. 31, 2013 Restricted Stock Grants [Member]	Dec. 31, 2012 Restricted Stock Grants [Member]	Dec. 31, 2011 Restricted Stock Grants [Member]	Dec. 31, 2013 Restricted Stock Grants [Member] Executive Officers [Member]	Dec. 31, 2012 Restricted Stock Grants [Member] Executive Officers [Member]	Dec. 31, 2013 Restricted Stock Grants [Member] Non-Employee Members of Board of Directors [Member]	Dec. 31, 2012 Restricted Stock Grants [Member] Non-Employee Members of Board of Directors [Member]	Dec. 31, 2011 Restricted Stock Grants [Member] Non-Employee Members of Board of Directors [Member]	Dec. 31, 2013 Restricted Stock Grants [Member] Consultant [Member]	Dec. 31, 2013 Employee Stock Option [Member]	Dec. 31, 2012 Employee Stock Option [Member]	Dec. 31, 2011 Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized				10,999	4,200	1,050
Percentage increase in the number of shares authorized for issuance under the Incentive Plan				2.50%
Shares granted							594	563	6	575	552	11	11	6	8
Percentage of shares to vest each year										20.00%
Vesting period										5 years		1 year				4 years		5 years
Unrecognized share-based compensation cost							$ 16,315									$ 5,314
Costs are expected to be recognized over a weighted average period							2 years 4 months 24 days									1 year 4 months 24 days
Expiration period of options																10 years		10 years
Options granted																25	0	1,250
Cash received from stock option exercises	16,278	8,049	1,681
Dividend yield assumption	0.00%	0.00%	0.00%
Minimum eligible age to participate in the plan	21
University made discretionary matching contributions	$ 1,400	$ 1,080	$ 933