Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Components of accumulated other comprehensive loss
Currency translation adjustments, Beginning Balance	$ (16.5)	$ (17.1)	$ (17.1)
Currency translation adjustments, Other comprehensive income (loss) before reclassification	0	0	0
Currency translation adjustments, Amounts reclassified from accumulated other comprehensive loss, net of tax	0	0.6	0
Currency translation adjustments, Amounts reclassified from accumulated other comprehensive loss, tax benefit	0	0.4	0
Currency translation adjustments, Less: noncontrolling interest	0	0	0
Currency translation adjustments, Other comprehensive income (loss)	0	0.6	0
Currency translation adjustments, Ending Balance	(16.5)	(16.5)	(17.1)
Unrealized loss on derivative financial instruments, Beginning Balance	(34.8)	(46.2)	(36.3)
Unrealized loss on derivative financial instruments, Other comprehensive income (loss) before reclassifications	0.8	7.2	(3.9)
Unrealized loss on derivative financial instruments, Amounts reclassified from accumulated other comprehensive loss, net of tax	18.1	5.8	4.1
Unrealized loss on derivative financial instruments, Amounts reclassified from accumulated other comprehensive loss, tax benefit	8.7	3.2	2.3
Unrealized loss on derivative financial instruments, Less: noncontrolling interest	(4.2)	(1.6)	(0.1)
Unrealized loss on derivative financial instruments, Other comprehensive income (loss)	14.7	11.4	0.1
Unrealized loss on derivative financial instruments, Reclassification of purchase of additional interest in TRIP Holdings			(15.5)
Unrealized loss on derivative financial instruments, Tax expense allocation related to TRIP Holdings unrealized loss on derivative financial instruments			5.5
Unrealized loss on derivative financial instruments, Sale of interests in partially-owned leasing subsidiaries	13.2
Unrealized loss on derivative financial instruments, Repurchase of interests in partially-owned leasing subsidiary	(11.8)
Unrealized loss on derivative financial instruments, Ending Balance	(18.7)	(34.8)	(46.2)
Net actuarial gains/(losses) of defined benefit plans, Beginning Balance	(98.8)	(70.7)	(42.1)
Net actuarial gains/(losses) of defined benefit plans, Other comprehensive income (loss) before reclassifications	52.7	(30.3)	(29.8)
Net actuarial gains/(losses) of defined benefit plans, Amounts reclassified from accumulated other comprehensive loss, net of tax	3.1	2.2	1.2
Amortization of net actuarial losses, tax benefit	1.9	1.1	0.6
Net actuarial gains/(losses) of defined benefit plans, Less: noncontrolling interest	0	0	0
Net actuarial gains/(losses) of defined benefit plans, Other comprehensive income (loss)	55.8	(28.1)	(28.6)
Net actuarial gains/(losses) of defined benefit plans, Ending Balance	(43.0)	(98.8)	(70.7)
Accumulated Other Comprehensive Loss, Beginning Balance	(150.1)	(134.0)	(95.5)
Accumulated Other Comprehensive Loss, Other comprehensive income (loss) before reclassifications	53.5	(23.1)	(33.7)
Accumulated Other Comprehensive Loss, Amounts reclassified from accumulated other comprehensive loss, net of tax	21.2	8.6	5.3
Accumulated Other Comprehensive Loss, Amounts reclassified from accumulated other comprehensive loss, tax benefit	10.6	4.7	2.9
Accumulated Other Comprehensive Loss, Less: noncontrolling interest	(4.2)	(1.6)	(0.1)
Accumulated Other Comprehensive Loss, Other comprehensive income (loss)	70.5	(16.1)	(28.5)
Accumulated Other Comprehensive Loss, Ending Balance	(78.2)	(150.1)	(134.0)
Statement [Line Items]
Before-tax reclassification of net actuarial gains/(losses) of defined benefit plans included in cost of revenues	(4.9)	(3.2)	(1.7)
Cost of revenues
Statement [Line Items]
Before-tax reclassification of net actuarial gains/(losses) of defined benefit plans included in cost of revenues	$ 4.0	$ 2.7	$ 1.5