Fair Value Measurements (Summary Of Changes In Level 3 Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Fair Value Disclosures [Abstract]
Derivatives, Beginning of Period	$ 29,331		$ 25,228
Total gains included in net income	(11,061)		(1,661)
Total gains included in other comprehensive income	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Derivatives, End of Period	18,270		23,567
Net unrealized gains included in net income relating to liabilities held at March 31, 2012 and 2011	$ 11,061	[1]	$ 1,661	[1]

[1] Included in net investment income in the consolidated statements of income and comprehensive income.