Contingencies - Narrative (Details)							1 Months Ended
	Apr. 26, 2015	Jan. 13, 2014 USD ($)	Dec. 23, 2013 USD ($)	Dec. 21, 2013 USD ($)	Jan. 24, 2013 USD ($)	Aug. 11, 2011 USD ($)	Aug. 31, 2011 USD ($)	Apr. 30, 2011 USD ($) trade_secret	Jan. 31, 2010 USD ($)	Jun. 30, 2006 Case	Apr. 30, 1999 USD ($)	Mar. 31, 2019 USD ($)	Nov. 11, 2014 USD ($)	Jul. 26, 2013 USD ($)	Dec. 31, 2012 USD ($)	Apr. 27, 2009 USD ($)	Jul. 17, 2008 USD ($)
MGA
Loss Contingencies [Line Items]
Number of cases combined | Case										3
Historical jury verdict																$ 100,000,000	$ 100,000,000
Number of claimed trade secrets | trade_secret								26
Compensatory damages awarded by jury								$ 88,500,000
Number of other claimed trade secrets | trade_secret								88
Reduced compensatory damages awarded by court							$ 85,000,000.0
Punitive damages awarded							85,000,000.0
Attorney fees and costs awarded							140,000,000
Compensatory damages, punitive damages, and attorney fees and costs awarded by court							$ 310,000,000
Damages for alleged trade secret misappropriation appealed						$ 170,000,000
Attorney fees and costs appealed						$ 140,000,000
Amount of damages and attorney's fees and costs vacated by the appeals court					$ 172,500,000
Litigation accrual															$ 138,000,000
Approximate amount of judgment finalized in the District Court, including interest				$ 138,000,000
Payment of judgment			$ 138,000,000
Accrued litigation liability												$ 0
Yellowstone
Loss Contingencies [Line Items]
Alleged loss of profits											$ 1,000,000
Unpaid accounts receivable											4,000,000
Alleged business investments											3,000,000
Initial estimate of loss of profits											$ 1,000,000
Court awarded damages from counterclaim									$ 4,000,000
Damages awarded, including attorney fees, inflation and interest														$ 17,000,000
Counter claim awarded, including inflation													$ 7,500,000	$ 7,500,000
Damages award including inflation and interest													$ 14,500,000
Fine on claims (as a percent)	1.00%
Minimum | MGA
Loss Contingencies [Line Items]
Alleged trade secrets damages claimed (more than)		$ 1,000,000,000