|
Debt (Details Textual) (USD $)
|
1 Months Ended | 3 Months Ended | 3 Months Ended | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
May 31, 2012
|
Mar. 31, 2013
|
Mar. 31, 2012
|
Dec. 31, 2012
|
Mar. 31, 2013
Minimum [Member]
|
Mar. 31, 2013
Maximum [Member]
|
Mar. 31, 2013
Interest Rate Swap [Member]
|
May 31, 2012
Credit facilities due May 2017 [Member]
|
Mar. 31, 2013
$99.5 million 9.250% debentures due May 2021 [Member]
|
Mar. 31, 2013
$360.0 million 7.400% debentures due September 2035 [Member]
|
Dec. 31, 2012
Eurodollar rate borrowings [Member]
|
Mar. 31, 2013
Credit facilities due 2016 [Member]
|
Dec. 31, 2012
Credit facilities due 2016 [Member]
|
Mar. 31, 2012
Uncommitted revolver, original borrowing capacity [Member]
|
Jul. 31, 2012
Uncommitted revolver, amended borrowing capacity [Member]
|
Mar. 31, 2013
Fixed Rate Senior Notes [Member]
|
Dec. 31, 2012
Fixed Rate Senior Notes [Member]
|
|
| Debt Instrument [Line Items] | |||||||||||||||||
| Non-cash write-off of deferred issuance costs | $ (1,800,000) | $ 0 | |||||||||||||||
| Revolving credit facility maximum borrowing capacity | 1,250,000,000.00 | 75,000,000 | 125,000,000 | ||||||||||||||
| Aggregate amount under Amended and Restated Credit Facility | 500,000,000 | ||||||||||||||||
| Reduced amount of existing credit facility | 1,000,000,000.0 | ||||||||||||||||
| Interest rate (in percentage) | 9.25% | 7.40% | 1.32% | ||||||||||||||
| Debt | 25,000,000 | ||||||||||||||||
| Letters of credit utilizing availability under Credit Facilities | 730,600,000 | 909,400,000 | |||||||||||||||
| Balance availability under Letters of Credit Facilities | 1,519,400,000 | 1,315,600,000 | |||||||||||||||
| Percentage of tax exempt financings | 85.00% | ||||||||||||||||
| Capital lease liabilities | 88,900,000 | 87,000,000 | |||||||||||||||
| Range of capital lease liabilities matured | 2013 | 2046 | |||||||||||||||
| Fair value of our fixed rate senior notes | 6,800,000,000 | 6,900,000,000 | |||||||||||||||
| Carrying value of fixed rate senior notes | 5,800,000,000 | 5,800,000,000 | |||||||||||||||
| Accumulated and other comprehensive income, net of tax | 24,200,000 | 24,600,000 | |||||||||||||||
| Expected to amortization of yield adjustment on senior notes | 2,500,000 | ||||||||||||||||
| Effective portion of interest rate locks amortized as an adjustment to interest expense | $ 600,000 | $ 500,000 | |||||||||||||||