Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 07, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Unaccrued Contractual Commitments and Employee Separation Expenses [Line Items]
Unaccrued contractual and other commitments		$ 18.6		$ 18.6
Ronald Rubin's [Member]
Unaccrued Contractual Commitments and Employee Separation Expenses [Line Items]
Employee Separation Expense, Incurred to Date				4.5
Provision for cash separation agreement		0.8	0.3	1.9	0.3	2.6
Restricted shares granted under Equity Incentive Plan				16,000
Restricted shares granted, fair value		0.3		0.3
Restricted shares granted, fair value per share		$ 18.28		$ 18.28
Restricted shares granted, vesting period				1 year
Founder's retirement payment	3.5
Edward Glickman [Member]
Unaccrued Contractual Commitments and Employee Separation Expenses [Line Items]
Provision for cash separation agreement			$ 0.5		$ 0.5