Goodwill and Other Intangibles - Other Intangible (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Other Intangible Assets
Gross Carrying Amount	$ 41,883		$ 41,883		$ 42,456
Accumulated Amortization	28,402		28,402		28,416
Other intangible assets not subject to amortization	8,900		8,900
Amortization expense of other intangible assets	300	$ 400	513	$ 700
Trade names
Other Intangible Assets
Gross Carrying Amount	8,525		8,525		8,529
Trading rights
Other Intangible Assets
Gross Carrying Amount	339		339		339
Other
Other Intangible Assets
Gross Carrying Amount	50		50		50
POSIT trade name
Other Intangible Assets
Other intangible assets not subject to amortization	8,400		8,400
Customer related intangibles
Other Intangible Assets
Gross Carrying Amount	9,691		9,691		10,217
Accumulated Amortization	6,018		$ 6,018		6,219
Useful Lives			17 years
Proprietary software
Other Intangible Assets
Gross Carrying Amount	23,278		$ 23,278		23,321
Accumulated Amortization	$ 22,384		$ 22,384		$ 22,197
Useful Lives			8 years 4 months 24 days