Revenues from contracts with customers (Contract Assets and Liabilities) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Jan. 01, 2018
Capitalized Contract Cost [Line Items]
Contract assets	$ 23,652	$ 18,631
Deferred income, IRA fees	1,169	0
Cost of Goods and Services Sold	1,500
Commission
Capitalized Contract Cost [Line Items]
Contract assets	2,867	2,007
Mutual Fund Income
Capitalized Contract Cost [Line Items]
Contract assets	7,364	7,779
Advisory fees
Capitalized Contract Cost [Line Items]
Contract assets	681	1,460
Bank Deposit Sweep Income
Capitalized Contract Cost [Line Items]
Contract assets	3,849	3,459
Investment Banking Fees
Capitalized Contract Cost [Line Items]
Contract assets	5,601	3,926
Other Income [Member]
Capitalized Contract Cost [Line Items]
Contract assets	3,290	0
Investment Banking Fees
Capitalized Contract Cost [Line Items]
Deferred income, IRA fees	407	0
IRA fees
Capitalized Contract Cost [Line Items]
Deferred income, IRA fees	$ 762	$ 0

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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

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-Publisher FASB
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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

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The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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