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Securities Available For Sale (Narrative) (Detail) (Auction Rate Securities [Member], USD $) In Millions, unless otherwise specified | 6 Months Ended | 39 Months Ended | 6 Months Ended |  |  |  | 0 Months Ended | 6 Months Ended | 42 Months Ended |  | 3 Months Ended | 42 Months Ended
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Jun. 30, 2013 | Dec. 31, 2012 | Jun. 30, 2013 Minimum [Member] | Jun. 30, 2013 Maximum [Member] | Jun. 30, 2013 Asset-backed Securities [Member] | Dec. 31, 2012 Asset-backed Securities [Member] | Jun. 30, 2013 Asset-backed Securities [Member] Minimum [Member] Y | Jun. 30, 2013 Asset-backed Securities [Member] Maximum [Member] Y | Dec. 31, 2012 Collateralized Debt Obligations [Member] | Jun. 30, 2013 Collateralized Debt Obligations [Member] Minimum [Member] | Jun. 30, 2013 Collateralized Debt Obligations [Member] Maximum [Member] | Mar. 31, 2013 Securities Redeemed or Sold [Member] | Mar. 31, 2013 Securities Redeemed or Sold [Member] Other Comprehensive Income (Loss) [Member] | Jun. 30, 2013 Securities Redeemed or Sold [Member] Asset-backed Securities [Member] | Mar. 31, 2013 Securities Redeemed or Sold [Member] Asset-backed Securities [Member] | Mar. 31, 2013 Securities Redeemed or Sold [Member] Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Auction rate securities, sold at par |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2.6 |  |
Auction rate securities, par value | 10.3 | 17.9 |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.6 |  |  | 2.6 | 5.0
Adjusted cost basis |  | 14.6 | [1] |  |  | 10.3 | [1] | 12.9 | [1] |  |  | 1.7 | [1] |  |  | 4.3 |  |  | 2.6 | 1.7
Investment, debt security, default rate of underlying assets |  |  |  |  |  |  |  |  |  |  |  | 6.22% |  | 8.00% | 9.00% |  |  |  |  |
Available-for-sale securities, gross unrealized gain (loss) |  | (0.2) |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.1 | 0.7 |  | (0.2) | 1.3
Deferred tax liabilities, tax deferred income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.4 |  |  |  |
Auction-rate securities yield rate |  |  |  | 1.46% | 1.92% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative credit and other losses recognized in earnings | $ 0 | $ 3.3 |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3.3 |  |  | $ 0 | $ 3.3
Contractual maturities of securities, in years |  |  |  |  |  |  |  |  |  | 15 | 34 |  |  |  |  |  |  |  |  |
[1] | Adjusted cost basis reflects adjustments for credit and other losses recognized in earnings on our structured finance security. There were no adjustments to the cost basis of securities held as of June 30, 2013. Cumulative adjustments to the cost basis of securities held as of December 31, 2012 totaled $3.3 million. Par value of securities held as of June 30, 2013 and December 31, 2012 totaled $10.3 million and $17.9 million, respectively.

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- Definition The interest rate for investments that have an interest rate. For fixed rate investments, this indicates the fixed interest rate. If the investment has a variable interest rate, the rate stated here may be the rate that is currently relevant. In this case the "Investment, Interest Rate is Current Rate for Variable Rate Investment Flag", "Investment, Interest Rate is Discount Rate at Purchase Flag", "Investment, Interest Rate Reflects Current Yield Flag" should be used. If one of these flags are not appropriate to explain the interest rate that is indicated, then a new flag should be added or an explanation should be included in "Investment, Additional Information". + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 12 -Sentence Column A + Details
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- Definition This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition The net amount of gross unrealized gains (losses) for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 + Details
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- Definition The aggregate value of securities held, which were categorized neither as trading nor held-to-maturity, for which the interest rate reset through an auction process, that failed to be liquidated through auction, and which were sold at par value during the period. + References No definition available. + Details
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from tax deferred revenue or other income not separately disclosed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=6969291&loc=d3e28680-109314 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 11 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition This item represents the default rate of the underlying assets in the security that was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are other than temporarily impaired and the amount of such impairment determined to be related to credit loss recognized in earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 18A -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 7 -Footnote 2 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 15D -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 15C -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 16B -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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