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Income Tax Expense - NOL and Tax Credit Carryforwards (Details) (USD $) | Dec. 31, 2013 | Dec. 31, 2012
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Federal [Member] |  |  |  |
NOL and Tax Credit Carryforwards [Line Items] |  |  |  |
NOL Carryforward | $ 279,800,000 | [1] | $ 244,100,000 | [1]
Tax Credit Carryforwards | 35,500,000 |  | 16,000,000 |
NOL and Federal Tax Credit Carryforwards, Valuation Allowance | 0 |  |  |
State [Member] |  |  |  |
NOL and Tax Credit Carryforwards [Line Items] |  |  |  |
NOL Carryforward | 156,300,000 | [1] | 90,600,000 | [1]
Tax Credit Carryforwards | 11,900,000 | [2] | 10,300,000 | [2]
State Tax Credit Carryforwards, Valuation Allowance | $ 7,700,000 |  |  |
[1] | Pretax amounts
[2] | Net of $7.7 million valuation allowance.

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- Definition Operating Loss and Tax Credit Carryforwards, Valuation Allowance + References No definition available. + Details
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- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
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- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Carryforwards -URI http://asc.fasb.org/extlink&oid=6506874 + Details
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- Definition Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Valuation Allowance -URI http://asc.fasb.org/extlink&oid=6528051 + Details
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