Summary of Significant Accounting Policies (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011 item	Dec. 31, 2010
Goodwill and Other Intangible Assets
Goodwill	$ 1,380,689,000	$ 1,180,359,000	$ 1,185,756,000
Other intangible assets	706,477,000	421,593,000
Goodwill as a percentage of total assets	24.50%
Other intangible assets as a percentage of total assets	12.50%
Number of issues that arise with respect to assets that require significant management estimates and judgment	2
Accounting for Derivatives and Hedging Activities
Number of variable interest payment obligations		2
Reference rate of swap yield curve used to determine fair value of interest rate swaps		LIBOR
Loss in OCI related to interest rate swap contracts qualified for cash flow hedge accounting		4,700,000
Notional value of cash flow hedges		440,000,000
Notional value of interest rate swap contracts expiring in October 2011		$ 200,000,000
Land improvements | Maximum
Estimated useful lives of property and equipment
Useful lives	15 years
Land improvements | Minimum
Estimated useful lives of property and equipment
Useful lives	5 years
Building and improvements | Maximum
Estimated useful lives of property and equipment
Useful lives	40 years
Building and improvements | Minimum
Estimated useful lives of property and equipment
Useful lives	5 years
Furniture, fixtures and equipment | Maximum
Estimated useful lives of property and equipment
Useful lives	31 years
Furniture, fixtures and equipment | Minimum
Estimated useful lives of property and equipment
Useful lives	3 years