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Stock-Based Compensation - Additional Information (Detail) (USD $) | 12 Months Ended | 1 Months Ended | 12 Months Ended |  | 12 Months Ended | 3 Months Ended | 12 Months Ended
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Dec. 31, 2012 Y | Dec. 31, 2011 | Dec. 31, 2010 | Mar. 31, 2010 Class C common unit interests [Member] | Dec. 31, 2012 Class C common unit interests [Member] | Dec. 31, 2012 Performance Share Unit Awards [Member] | Jul. 30, 2012 Performance Share Unit Awards [Member] | Dec. 31, 2012 Performance Share Unit Awards [Member] Minimum [Member] | Dec. 31, 2012 Performance Share Unit Awards [Member] Maximum [Member] | Dec. 31, 2010 Discretionary stock awards [Member] | Dec. 31, 2012 Discretionary stock awards [Member] | Dec. 31, 2011 Discretionary stock awards [Member] | Dec. 31, 2010 Discretionary stock awards [Member] Class C common unit interests [Member] | Dec. 31, 2012 Restricted stock awards [Member] | Dec. 31, 2011 Restricted stock awards [Member] | Dec. 31, 2010 Restricted stock awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation expense | $ 10,333,000 | $ 3,656,000 | $ 9,970,000 |  |  | $ 400,000 |  |  |  |  |  |  |  | $ 10,200,000 | $ 3,700,000 | $ 1,200,000
Unrecognized expense of outstanding PSUs |  |  |  |  |  | 3,600,000 |  |  |  |  |  |  |  | 17,200,000 |  |
Unrecognized expense recognition period, years | 2 years 2 months 12 days |  |  |  |  | 3 years 7 months 6 days |  |  |  |  |  |  |  |  |  |
Fair value of awards vested | 11,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Right to received shares of common stock |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |
Performance share units initial performance period, years | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PSU granted percentage of earnings |  |  |  |  |  |  |  | 0.00% | 200.00% |  |  |  |  |  |  |
Amortized performance period |  |  |  |  |  | 4 years |  |  |  |  |  |  |  |  |  |
Number of trading days | 30 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation expense recorded |  |  |  | $ 5,200,000 | $ 0 |  |  |  |  | $ 3,500,000 | $ 0 | $ 0 | $ 8,700,000 |  |  |
Common units granted in period | 753,285 | 248,228 |  | 1,000,000 |  | 155,220 |  |  |  |  |  |  |  |  |  |
Percentage of fair value allocable |  |  |  | 95.00% |  |  |  |  |  |  |  |  |  |  |  |
Expected volatility rate |  |  |  | 60.00% |  | 51.00% |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  | 2.08% |  | 0.46% |  |  |  |  |  |  |  |  |  |
Expected liquidity term, years |  |  |  | 4 years |  | 4 years 2 days |  |  |  |  |  |  |  |  |  |

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- Definition Percentage Of Fair Value Allocated To C Unit Shareholders + References No definition available. + Details
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- Definition Percentage Of Performance Share Awards Based On Shareholder Return + References No definition available. + Details
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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (C-units and discretionary shares) with employees and certain consultants qualifying for treatment as employees distributed from predecessor's capital members. + References No definition available. + Details
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- Definition As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph h -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 Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 -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 Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(c) -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 total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph c(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. + Details
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.D.2) -URI http://asc.fasb.org/extlink&oid=6793087&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section D -Subsection 2 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(b) -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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