Goodwill and Other Intangible Assets (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense related to intangible assets	$ 1,703	$ 2,429	$ 3,325
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets estimated lives, years	5 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets estimated lives, years	10 years
Insurance [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period		284
Finite-lived Intangible Assets Acquired		$ 405