Securities Available For Sale (Auction Rate Securities Reconciliation Of Cost Basis To Fair Value) (Detail) (USD $)	9 Months Ended		27 Months Ended		36 Months Ended						36 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011 Auction Rate Securities [Member]		Sep. 30, 2012 Auction Rate Securities [Member]		Sep. 30, 2012 Asset-backed Securities [Member] Auction Rate Securities [Member]		Dec. 31, 2011 Asset-backed Securities [Member] Auction Rate Securities [Member]		Sep. 30, 2012 Collateralized Debt Obligations [Member] Auction Rate Securities [Member]		Dec. 31, 2011 Collateralized Debt Obligations [Member] Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost Basis			$ 14,600,000	[1]	$ 14,600,000	[1]	$ 12,900,000	[1]	$ 12,900,000	[1]	$ 1,700,000	[1]	$ 1,700,000	[1]
Gross Cumulative Unrealized (Losses)/Gains											700,000		0
Gross Cumulative Unrealized (Losses)/Gains							(1,200,000)		(1,000,000)
Fair Value							11,700,000		11,900,000
Gross Cumulative Unrealized (Losses)/Gains			(1,000,000)		(500,000)
Fair Value			13,600,000	[2]	14,100,000	[2]					2,400,000		1,700,000
Par value of securities held			17,900,000		17,900,000						5,000,000
Cumulative credit and other losses recognized in earnings	$ 0	$ 457,000	$ 3,300,000		$ 3,300,000						$ 3,300,000

[1] Adjusted cost basis reflects adjustments for credit and other losses recognized in earnings. Cumulative adjustments to the cost basis of securities held as of both September 30, 2012 and December 31, 2011 totaled $3.3 million. Par value of securities held as of both September 30, 2012 and December 31, 2011 was $17.9 million.

[2] The Company’s auction rate securities maintain split ratings. For purposes of this table, securities are categorized according to their lowest rating.