Acquisitions - Con-way Inc. - Additional Information (Details) $ / shares in Units, employee in Thousands, customer in Thousands, $ in Millions			3 Months Ended
	Oct. 30, 2015 USD ($)	Sep. 09, 2015 USD ($) employee Location customer $ / shares shares	Mar. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($)
Business Acquisition [Line Items]
Common stock, par value (in usd per share) | $ / shares			$ 0.001	$ 0.001
Goodwill			$ 4,787.0	$ 4,610.6	$ 967.8
Con-Way
Business Acquisition [Line Items]
Number of locations where the entity operates | Location		582
Number of employees | employee		30
Number of customers (over) | customer		36
Common stock, par value (in usd per share) | $ / shares		$ 0.625
Common stock price per share (in usd per share) | $ / shares		$ 47.60
Number of shares acquired that were validly tendered and not properly withdrawn | shares		46,150,072
Percentage of shares validly tendered and not properly withdrawn acquired		81.10%
Number of shares with guaranteed delivery | shares		1,793,225
Percentage of common stock acquired		3.20%
Consideration	$ 2,317.8
Business Combination, Consideration Transferred, Cash Acquired	437.3
Cash consideration	2,706.6
Portion of replacement equity awards attributable to pre-acquisition service	17.6
Liability for performance share settlement	30.9
Goodwill	$ 1,306.9
Increase (decrease) in depreciation and amortization			$ (5.8)
Con-Way | Transportation
Business Acquisition [Line Items]
Goodwill		$ 1,025.7
Con-Way | Logistics
Business Acquisition [Line Items]
Goodwill		$ 281.2