Acquisition of New York Code and Design Academy - Purchase Price Allocation (Details) - USD ($)		3 Months Ended			9 Months Ended
	Jan. 13, 2016	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 20,744,000			$ 20,744,000		$ 20,744,000
Cash paid for acquisition, net of cash acquired						$ 7,635,000
Deferred payment arrangements value		3,200,000			$ 3,200,000		$ 3,400,000
New York Code And Design Academy, Inc.
Business Acquisition [Line Items]
Cash	$ 790,000
Other assets	1,265,000
Trade name	5,660,000
Goodwill	13,944,000
Liabilities assumed	(4,734,000)
Total assets acquired and liabilities assumed, net	16,925,000
Less: contingent consideration	(14,500,000)
Cash paid for acquisition, net of cash acquired	1,635,000
Discount rate					4.50%
Reduction in fair value of contingent consideration		5,500,000	$ 2,300,000	$ 0		$ 0
Deferred payment arrangements value		0			$ 0
New York Code And Design Academy, Inc. | Maximum
Business Acquisition [Line Items]
Contingent consideration		$ 11,500,000			$ 11,500,000
New York Code And Design Academy, Inc. | Contingent Consideration Results of Operations Over Five Year Period [Member]
Business Acquisition [Line Items]
Contingent consideration	12,500,000
New York Code And Design Academy, Inc. | Contingent Consideration Receipt Of State Regulatory Permit [Member]
Business Acquisition [Line Items]
Contingent consideration	5,500,000
New York Code And Design Academy, Inc. | Contingent Consideration Accelerated Earnout Upon Receipt Of One State Regulatory Permit [Member]
Business Acquisition [Line Items]
Contingent consideration	$ 1,000,000