Derivative Financial Instruments (Notional Amounts, Weighted-Average Fixed Rates, And Terms Associated With The Company's Interest Rate Swaps) (Details) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 Derivative Remaining Term Year One [Member] USD ($)		Dec. 31, 2011 Derivative Remaining Term Year One [Member] U.S. [Member] USD ($)	Dec. 31, 2011 Derivative Remaining Term Year One [Member] U.K. [Member] GBP (£)	Dec. 31, 2011 Derivative Remaining Term Year Two [Member] USD ($)		Dec. 31, 2011 Derivative Remaining Term Year Two [Member] U.S. [Member] USD ($)	Dec. 31, 2011 Derivative Remaining Term Year Two [Member] U.K. [Member] GBP (£)	Dec. 31, 2011 Derivative Remaining Term Year Three [Member] USD ($)		Dec. 31, 2011 Derivative Remaining Term Year Three [Member] U.S. [Member] USD ($)	Dec. 31, 2011 Derivative Remaining Term Year Four [Member] USD ($)		Dec. 31, 2011 Derivative Remaining Term Year Four [Member] U.S. [Member] USD ($)	Dec. 31, 2011 Derivative Remaining Term Year Five [Member] USD ($)		Dec. 31, 2011 Derivative Remaining Term Year Five [Member] U.S. [Member] USD ($)
Derivative [Line Items]
Notional Amounts		$ 827,451	[1]	$ 750,000	£ 50,000	$ 788,726	[1]	$ 750,000	£ 25,000	$ 750,000	[1]	$ 750,000	$ 550,000	[1]	$ 550,000	$ 350,000	[1]	$ 350,000
Weighted Average Fixed Rate		3.45%				3.35%				3.29%			3.27%			3.28%
Exchange Rate	1.55

[1] United Kingdom pound sterling amounts have been converted into United States dollars at approximately $1.55 to £1.00, which was the exchange rate in effect as of December 31, 2011.