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Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended								12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2013 Performance Share Unit Awards [Member]	Dec. 31, 2012 Performance Share Unit Awards [Member]	Jul. 30, 2012 Performance Share Unit Awards [Member]	Dec. 31, 2013 Performance Share Unit Awards [Member] Minimum [Member]	Dec. 31, 2013 Performance Share Unit Awards [Member] Maximum [Member]	Dec. 31, 2013 Restricted stock awards [Member]	Dec. 31, 2012 Restricted stock awards [Member]	Dec. 31, 2011 Restricted stock awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	7,200,000
Annual Forfeiture Rate				0.00%	11.00%	2.70%
Expected percentage of PSUs earned	112.00%	98.00%
Stock-based compensation expense	$ 11,982,000	$ 10,333,000	$ 3,656,000			$ 1,800,000	$ 400,000				$ 10,200,000	$ 10,200,000	$ 3,700,000
Unrecognized expense						6,800,000					24,800,000
Unrecognized expense recognition period, years						2 years 11 months 2 days					2 years
Fair value of awards vested											6,500,000
Right to received shares of common stock								1
Performance share units initial performance period, years						3 years
PSU granted percentage of earnings									0.00%	200.00%
Number of trading days						30 days
Common units granted in period						135,620	155,220				594,895	753,285
Expected volatility rate						47.48%	51.00%
Risk-free interest rate						0.65%	0.46%
Expected liquidity term, years						4 years	4 years 0 months 2 days
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	$ 4,500,000	$ 4,000,000	$ 1,400,000

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The rate of forfeitures assumptions that is used in calculating the fair values of a share-based compensation award.

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Number Of Trading Days Consider For Average Closing Price

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Percentage Of Performance Share Awards Based On Shareholder Return

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Rights Received By Common Shareholder For Each Common Share Outstanding Rights

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The initial performance period for the performance share units.

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Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Output, Expected Percentage Earned

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Unrecognized cost of unvested share-based compensation awards.

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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.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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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.

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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).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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.

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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.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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