Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Interest rate hedges included in balance sheet
AOCL loss/(income)	$ (49.8)	$ (36.3)
Interest Rate Locks, 2005 to 2006 [Member]
Interest rate hedges included in balance sheet
Notional Amount	200.0
Interest Rate	4.87%
Liability	0
AOCL loss/(income)	(2.4)
Noncontrolling Interest	0
Interest rate hedges effect on interest expense - increase/(decrease)
Expected effect during next twelve months	(0.3)
Interest Rate Locks, 2006 to 2007 [Member]
Interest rate hedges included in balance sheet
Notional Amount	370.0
Interest Rate	5.34%
Liability	0
AOCL loss/(income)	12.3
Noncontrolling Interest	0
Interest rate hedges effect on interest expense - increase/(decrease)
Expected effect during next twelve months	3.4
TILC warehouse [Member]
Interest rate hedges included in balance sheet
Notional Amount	200.0
Interest rate hedges effect on interest expense - increase/(decrease)
Expected effect during next twelve months	0
TRIP warehouse [Member]
Interest rate hedges included in balance sheet
Notional Amount	788.5
Interest Rate	3.60%
Liability	47.0
AOCL loss/(income)	25.3
Noncontrolling Interest	18.9
Interest rate hedges effect on interest expense - increase/(decrease)
Expected effect during next twelve months	6.3
2008 debt issuances [Member]
Interest rate hedges included in balance sheet
Notional Amount	489.4
Interest Rate	4.13%
Liability	45.7
AOCL loss/(income)	43.9
Noncontrolling Interest	0
Interest rate hedges effect on interest expense - increase/(decrease)
Expected effect during next twelve months	$ 18.2