Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Total World Fuel Shareholders' Equity	Noncontrolling Interest Equity
Balance as of beginning of period at Dec. 31, 2016	$ 1,940.0	$ 0.7	$ 399.9	$ 1,679.3	$ (154.8)	$ 1,925.0	$ 15.0
Balance (in shares) at Dec. 31, 2016		69.9
Increase (Decrease) in Shareholders' Equity
Net income	23.4			22.8		22.8
Cash dividends declared	(8.2)			(8.2)		(8.2)
Distribution of noncontrolling interest	(0.4)						(0.4)
Amortization of share-based payment awards	15.3		15.3			15.3
Issuance (cancellation) of common stock related to share-based payment awards	0.0
Issuance (cancellation) of common stock related to share-based payment awards (in shares)		(0.4)
Purchases of common stock tendered by employees to satisfy the required withholding taxes related to share-based payment awards	(4.0)		(4.0)			(4.0)
Purchases of common stock tendered by employees to satisfy the required withholding taxes related to share-based payment awards (in shares)		0.0
Purchases of common stock	(61.9)		(61.9)			(61.9)
Purchases of common stock (in shares)		(1.7)
Other comprehensive income (loss)	31.6				30.0	30.0	1.6
Balance as of end of period at Sep. 30, 2017	1,935.8	$ 0.7	349.3	1,693.9	(124.8)	1,919.0	16.8
Balance (in shares) at Sep. 30, 2017		67.7
Balance as of beginning of period at Dec. 31, 2017	$ 1,738.0	$ 0.7	354.9	1,492.8	(126.5)	1,721.9	16.0
Balance (in shares) at Dec. 31, 2017	67.7	67.7
Increase (Decrease) in Shareholders' Equity
Net income	$ 99.2			98.1		98.1	1.1
Cash dividends declared	(12.1)			(12.1)		(12.1)
Amortization of share-based payment awards	8.0		8.0			8.0
Issuance (cancellation) of common stock related to share-based payment awards	0.0
Issuance (cancellation) of common stock related to share-based payment awards (in shares)		0.2
Purchases of common stock tendered by employees to satisfy the required withholding taxes related to share-based payment awards	(2.2)		(2.2)			(2.2)
Purchases of common stock	(20.0)		(20.0)			(20.0)
Purchases of common stock (in shares)		(0.7)
Other comprehensive income (loss)	(31.4)				(30.2)	(30.2)	(1.2)
Reclassification of certain tax effects from U.S. Tax Reform	1.6			1.6		1.6
Balance as of end of period at Sep. 30, 2018	$ 1,781.2	$ 0.7	$ 340.8	$ 1,580.4	$ (156.7)	$ 1,765.2	$ 16.0
Balance (in shares) at Sep. 30, 2018	67.0	67.0