Acquisitions and Divestitures - Divestitures (Details) - USD ($)		3 Months Ended
	Oct. 31, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense		$ 31,174,000		$ 28,528,000
Faure Herman subsidiary | Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business	$ 21,800,000
Gain on sale of businesses - net			$ 9,300,000
Income tax expense			$ 0