Acquisition (Preliminary Purchase Price Allocation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 02, 2019	Jan. 01, 2019
Business Acquisition [Line Items]
Operating lease right-of-use assets	$ 92,852	$ 0			$ 103,694
Operating lease liabilities	(97,581)	0			$ (110,505)
Goodwill	0	$ 0	$ 6,914
Quarton
Business Acquisition [Line Items]
Operating lease right-of-use assets				$ 3,200
Intangible assets				22,200
Operating lease liabilities				(3,200)
Total estimated purchase price	103,000
Scenario, Plan | Quarton
Business Acquisition [Line Items]
Cash and cash equivalents				12,236
Fees receivable				7,269
Fixed assets				1,085
Intangible assets				22,200
Other assets				667
Compensation payable				637
Due to related parties				4,750
Accounts payable, accrued expenses and other liabilities				16,257
Total identifiable net assets acquired and liabilities assumed				$ 21,813
Goodwill	81,150
Total estimated purchase price	$ 102,963