Related Party Transactions - Narrative (Details) - Arthur J.Gallagher & Co - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Print services	$ 1.9	$ 1.7	$ 1.7
Insurance and risk management services	0.2	$ 0.6	$ 0.6
Related party receivable	$ 0.4