Equity - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Nov. 30, 2007
Stockholders Equity Note [Line Items]
Net effect of dilutive equity awards	2,222,440	0	2,274,311	0
Dilutive common shares outstanding, assuming conversion of convertible notes to common shares	11,825,450		7,644,075
Antidilutive equity awards outstanding	255,529	1,877,664	271,392	531,072
Stock repurchase program authorized number of shares to be repurchased					5,000,000
Stock repurchase program authorized number of shares remained for repurchase	4,005,985		4,005,985