Employee Stock Purchase Plan (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	2,755,337
Prior To Two Thousand Eleven [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	2,142,223
Price per ESPP Share Issued	$ 14.41
January 1 2012 To March 31 2012 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	82,619
Price per ESPP Share Issued	$ 12.29
April 1 2012 To June 30 2012 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	90,411
Price per ESPP Share Issued	$ 10.58
July 1 2012 To September 30 2012 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	83,269
Price per ESPP Share Issued	$ 11.75
October 1 2012 To December 31 2012 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	87,082
Price per ESPP Share Issued	$ 9.61
January 1 2013 To March 31 2013 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	90,799
Price per ESPP Share Issued	$ 9.45
April 1 2013 To June 30 2013 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	75,126
Price per ESPP Share Issued	$ 9.86
July 1 2013 To September 30 2013 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	50,982
Price per ESPP Share Issued	$ 14.63
October 1 2013 To December 31 2013 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ESPP Shares Issued	52,826
Price per ESPP Share Issued	$ 12.44