Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2012

Accounts Receivable [Abstract]

Net Accounts Receivable

	December 31,
		2012		2011
Billed utility revenue	$	54,294	$	47,311
Unbilled utility revenue		33,590		29,361
Other		9,358		3,359
		97,242		80,031
Less allowance for doubtful accounts		4,321		4,485
Net accounts receivable	$	92,921	$	75,546

Allowance For Doubtful Accounts

	2012		2011		2010
Balance at January 1,	$	4,485	$	4,367	$	4,790
Amounts charged to expense		4,805		4,854		4,156
Accounts written off		(5,939)		(5,780)		(5,489)
Recoveries of accounts written off		970		1,044		910
Balance at December 31,	$	4,321	$	4,485	$	4,367