Intangible Assets and Goodwill (Estimated Future Amortization Expense) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
2018	$ 18,201
2019	17,257
2020	17,197
2021	17,114
2022	12,843
Thereafter	382
Total other intangibles, net	$ 82,994	$ 116,499	$ 174,530