|
Significant Accounting Policies - Additional Information (Details) (USD $)
In Thousands, unless otherwise specified
|
12 Months Ended |
|
Dec. 31, 2013
Segment
|
Dec. 31, 2012
|
Dec. 31, 2011
|
| Schedule Of Equity Method Investments [Line Items] |
|
|
|
| Voting interest |
50.00% |
|
|
| Nonutility property estimated useful life, minimum (years) |
3 years |
|
|
| Nonutility property estimated useful life, maximum (years) |
50 years |
|
|
| Number of business reporting units for market based services |
4 |
|
|
| Estimated refunds |
$ 17,308 |
$ 19,698 |
|
| Amortization of contributions in aid of construction |
22,363 |
20,979 |
18,327 |
| Remediation costs accrued |
3,300 |
4,400 |
|
| Accrual for environmental loss contingencies payments |
1,100 |
|
|
| Regulatory assets |
8,027 |
8,656 |
|
|
Software
|
|
|
|
| Schedule Of Equity Method Investments [Line Items] |
|
|
|
| Acquisition cost, carrying value |
$ 303,798 |
$ 155,221 |
|
|
United States Government
|
|
|
|
| Schedule Of Equity Method Investments [Line Items] |
|
|
|
| Agreements range, high |
50 years |
|
|
|
Industries And Municipalities
|
|
|
|
| Schedule Of Equity Method Investments [Line Items] |
|
|
|
| Agreements range, high |
40 years |
|
|
| Agreements range, low |
2 years |
|
|