Fair Value Measurements (Detail) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 11, 2013	Jan. 31, 2014	Jun. 30, 2013	Nov. 30, 2012	Jan. 28, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares received in exchange for investment in loan (in shares)				49,136
Debtor in possession, fair value of shares received (in dollars per share)				$ 109
Convertible notes payable, current	$ 0	$ 346,000
Cash payment for debt redemption	13,215,000	15,500,000	3,000,000
3.75% Unsecured Convertible Subordinated Debentures Due In 2026
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, cost						9,800,000	6,000,000
School Specialties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debtor-in-possession financing, amount arranged								21,300,000
Shares received in exchange for convertible debentures (in shares)				26,457
Debtor in possession, cash received in exchange for investment in loan				17,500,000
Debtor in possession, gain on disposal of investment in loan				3,200,000
Debtor in possession, loss on disposal of loan				1,600,000
Cash And Cash Equivalent
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets		1,000,000
Marketable Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets		800,000
Face amount							11,900,000
Senior Notes | Convertible Senior Subordinted Notes Due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate (as a percent)	0.75%	0.75%
Convertible notes payable, current		300,000
Cash payment for debt redemption					$ 300,000