Acquisitions - Net Assets Acquired (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 18, 2019	Mar. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain		$ 2,700
Goodwill		$ 65,368	$ 16,955
Rhapsody America LLC
Business Acquisition [Line Items]
Business Combination, Step Acquisition, Initial Cash Consideration	$ 1,000
Business Combination, Contingent Consideration Paid	11,600
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	2,700
Business Combination, Consideration Transferred, Settlement of Debt and Warrants	6,408
Net purchase price	21,708
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	10,138
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	20,838
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	12,879
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restricted Cash	2,322
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	474
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease Assets	2,314
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Other	77
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	5,942
Intangible assets acquired	23,700
Goodwill	48,474
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	127,158
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	937
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Royalties and Fulfillment	71,980
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued and Other Liabilities, Current	7,475
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contract with Customer, Liability, Current	3,600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Notes Payable	12,115
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	6,061
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Liabilities, Noncurrent	1,197
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	1,515
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	104,880
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	22,278
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	570
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	$ 21,708