Current ratio of credit facility.

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Debt Instrument, Variable Interest Rate, Payable Assessment Period

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Equal redemption price percentage of principal amount of debt.

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Estimated annual payments, long term debt and other liabilities, due in the next twelve months.

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Estimated annual payments, long term debt and other liabilities, due in year five.

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Estimated annual payments, long term debt and other liabilities, due in year four.

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Estimated annual payments, long term debt and other liabilities, due in year three.

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Estimated annual payments, long term debt and other liabilities, due in year two.

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Interest rate in addition to LIBOR.

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Leverage ratio of long term debt to consolidated EBITDA.

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Loan origination fees paid to date. These fees are being amortized over the life of the agreement.

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Minimum redemption percentage of debt outstanding.

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Outstanding borrowings subject to LIBOR.

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Credit facility prohibits the payment of dividends over 0.25 of cni for preceding fiscal year.

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Percentage of maximum aggregate principal equity amount of the original principal amount that can be redeemed.

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Proceed from equity offerings redemption price percentage.

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Senior notes repurchase price in percentage for change of control.

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The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

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Interest rate stated in the contractual debt agreement.

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Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

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Amount borrowed under the credit facility as of the balance sheet date.

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The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Disclosure of timing of required repayments, sinking fund requirements, and other redeemable securities at fixed or determinable prices and dates in the five years immediately following the date of the latest balance sheet presented in the financial statements, and the amount thereafter to fully repay the principal of long-term debt. These disclosures may be made either on an individual debt or security basis, by type of debt or security basis, or on a combined basis.

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The total of the cash outflow during the period which has been paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt and the cost incurred directly for the issuance of equity securities.

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The cash inflow from a borrowing supported by a written promise to pay an obligation.

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The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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Long-Term Debt And Other Long-Term Liabilities (Narrative) (Details) (USD $)	0 Months Ended	6 Months Ended		0 Months Ended	6 Months Ended	0 Months Ended	6 Months Ended		0 Months Ended
	May 18, 2011	Jun. 30, 2012	Dec. 31, 2011	Sep. 13, 2011 Minimum [Member]	Jun. 30, 2012 Minimum [Member]	Sep. 13, 2011 Maximum [Member]	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Senior Unsecured Credit Facility [Member]	May 18, 2011 6.625% Senior Subordinated Notes Due 2021 [Member]	Jun. 30, 2012 6.625% Senior Subordinated Notes Due 2021 [Member]	Jun. 30, 2012 Line Of Credit Facility Lender Determined Amount [Member]	Jun. 30, 2012 Line Of Credit Facility Commitment Amount [Member]
Debt Instrument [Line Items]
Credit facility maturity date		May 24, 2012						September 13, 2016
Credit facility current credit amount											$ 600,000,000	$ 250,000,000
Credit facility maximum credit amount		750,000,000
Commitment fee percentage under credit facility				0.375%		0.50%
Origination, agency and syndication and other related fees		1,800,000
LIBOR plus interest rate					1.75%		2.50%
Payable assessment term for LIBOR		90 days
LIBOR interest rate plus one percent		LIBOR plus 1.00%
Outstanding borrowings subject to LIBOR		80,000,000
Outstanding borrowings		82,900,000	50,000,000
Maximum payment of dividends as a percentage of consolidated net income, prohibited under credit agreement							30.00%
Current ratio of credit facility		1 to 1
Leverage ratio of long-term debt		4 to 1
Aggregate principal amount									250,000,000
Interest percentage of senior subordinated notes									6.625%	6.625%
Proceeds from sale of notes									244,000,000
Deducting fees for debt issuance	6,000,000
Repayment of outstanding borrowings under unsecured credit facility	220,300,000
Percentage of maximum, aggregate principal equity amount		35.00%
Proceed from equity offerings redemption price percentage		106.625%
Minimum redemption percentage of debt outstanding		65.00%
Equal redemption price percentage of principal amount of debt		100.00%
Senior notes repurchase price in percentage		101.00%
2012		11,600,000
2013		22,200,000
2014		3,800,000
2015		3,100,000
2016		$ 85,600,000