Summary of Information about Restricted Stock Grants (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned Compensation	$ 6.8
November 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares	443,250
Vesting Schedule	3 equal annual installments commencing on October 20, 2012
Unearned Compensation	1.2
Remaining Period (in months)	10 months
November 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares	494,151
Vesting Schedule	3 equal annual installments commencing on October 20, 2013
Unearned Compensation	2.0
Remaining Period (in months)	22 months
August 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares	100,000
Vesting Schedule	3 equal annual installments commencing on October 20, 2014
Unearned Compensation	0.7
Remaining Period (in months)	34 months
November 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares	470,997
Vesting Schedule	3 equal annual installments commencing on October 20, 2014
Unearned Compensation	$ 2.9
Remaining Period (in months)	34 months