Goodwill and Intangible Assets (Schedule Of Acquired Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 259,323	$ 259,113
Accumulated amortization	122,841	103,744
Net	136,482	155,369
Client/broker contracts and relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	237,431	237,221
Accumulated amortization	102,756	84,581
Net	134,675	152,640
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	3,880	3,880
Accumulated amortization	3,563	3,492
Net	317	388
Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	14,646	14,646
Accumulated amortization	13,769	13,047
Net	877	1,599
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,232	2,232
Accumulated amortization	2,066	2,013
Net	166	219
Favorable lease arrangements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,134	1,134
Accumulated amortization	687	611
Net	$ 447	$ 523