Securities Available For Sale (Fair Value Of Auction Rate Securities By Security Type And Underlying Credit Rating) (Detail) (Auction Rate Securities [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	$ 14.4	[1]	$ 13.6	[1]
Underlying Credit Rating Aaa [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value			11.9	[1]
Underlying Credit Rating AA- [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	9.1	[1]
Underlying Credit Rating BB [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	2.6	[1]
Underlying Credit Rating CCC [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	2.7	[1]	1.7	[1]
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	2.7	[1]	1.7	[1]
Collateralized Debt Obligations [Member] | Underlying Credit Rating Aaa [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value			0	[1]
Collateralized Debt Obligations [Member] | Underlying Credit Rating AA- [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	0	[1]
Collateralized Debt Obligations [Member] | Underlying Credit Rating BB [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	0	[1]
Collateralized Debt Obligations [Member] | Underlying Credit Rating CCC [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	2.7	[1]	1.7	[1]
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	11.7	[1]	11.9	[1]
Asset-backed Securities [Member] | Underlying Credit Rating Aaa [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value			11.9	[1]
Asset-backed Securities [Member] | Underlying Credit Rating AA- [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	9.1	[1]
Asset-backed Securities [Member] | Underlying Credit Rating BB [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	2.6	[1]
Asset-backed Securities [Member] | Underlying Credit Rating CCC [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, fair value	$ 0	[1]	$ 0	[1]

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