Goodwill and Identifiable Assets Future Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 33,444	$ 39,628	$ 34,467
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2018	30,322
2019	23,287
2020	15,613
2021	12,753
2022	8,044
Thereafter	16,805
Net Carrying Amount	$ 106,824	$ 132,213