Commitments and Contingencies - Narrative (Details) € in Millions, $ in Millions										3 Months Ended	6 Months Ended		108 Months Ended
	Jan. 04, 2018 USD ($)	Nov. 06, 2017 defendant	May 03, 2017 lawsuit	Feb. 22, 2017 lawsuit	Jan. 31, 2017 USD ($) state item	May 02, 2016 defendant	Mar. 31, 2016	Feb. 04, 2015 defendant	Jan. 13, 2014 defendant	Mar. 31, 2015 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2014 USD ($)	Jan. 04, 2018 EUR (€)	Apr. 12, 2017 state	Mar. 31, 2017 item	Feb. 13, 2017 item
Commitments and Contingencies
Letters of credit outstanding and bank guarantees											$ 310.0
Maximum maturity year for letters of credit											2024
Letters of credit renewal option											1 year
Stock repurchased											$ 335.5	$ 250.0
Pending Litigation
Commitments and Contingencies
Range of possible loss, portion not accrued											$ 50.0
Pending Litigation | Defendants under the shareholder complaint filed in District Court, Douglas Country | Executive Officer
Commitments and Contingencies
Number of defendants | defendant									1
Pending Litigation | Defendants under the shareholder complaint filed in District Court, Douglas Country | Former Director
Commitments and Contingencies
Number of defendants | defendant									1
Pending Litigation | Defendants under the shareholder derivative complaints filed in US District Court for the District of Colorado
Commitments and Contingencies
Stock repurchased													$ 1,565.0
Period plaintiffs may file an amended complaint							30 days
Pending Litigation | Defendants under the shareholder derivative complaints filed in US District Court for the District of Colorado | Executive Officer
Commitments and Contingencies
Number of defendants | defendant								9
Pending Litigation | Defendants under the shareholder derivative complaints filed in US District Court for the District of Colorado | Director
Commitments and Contingencies
Number of defendants | defendant						6
Pending Litigation | Defendants under the shareholder derivative complaints filed in US District Court for the District of Colorado | Former Director
Commitments and Contingencies
Number of defendants | defendant						3
Pending Litigation | Lawrence Henry Smallen and Laura Anne Smallen Revocable Living Trust
Commitments and Contingencies
Number of purported class action lawsuits | lawsuit				2
Number of claims consolidated | lawsuit			2
Pending Litigation | Lawrence Henry Smallen and Laura Anne Smallen Revocable Living Trust | Executive Officer
Commitments and Contingencies
Number of defendants | defendant		2
Number of defendants voluntarily dismissed | defendant		1
Pending Litigation | National Court of Spain
Commitments and Contingencies
Guaranty liabilities | €														€ 23
Pending Litigation | National Court of Spain | Former Agent
Commitments and Contingencies
Number of agents | item																	98
Settled Litigation | Joint Settlement Agreements
Commitments and Contingencies
Number of state attorneys general | state					49										1
Count- criminal information | item					2
Compensation payment					$ 586.0
State attorneys general payment					$ 5.0
Period to retain an independent compliance auditor					3 years
Civil penalty assessed by the FinCEN Agreement					$ 184.0
Settled Litigation | Northern District of Illinois
Commitments and Contingencies
Litigation settlement awarded to other party										$ 8.5
Settled Litigation | NYDFS Consent Order
Commitments and Contingencies
Damages awarded	$ 60.0
Period to provide remediation plan	90 days
Settled Litigation | NYDFS Consent Order | Current Agent
Commitments and Contingencies
Number of agents | item																1
Settled Litigation | NYDFS Consent Order | Former Agent
Commitments and Contingencies
Number of agents | item																2