Commitments and Contingencies, Variable Interest Entities (Details) (Low-Income Housing Limited Partnerships [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Low-Income Housing Limited Partnerships [Member]
Amounts Reflected in Consolidated Balance Sheets [Abstract]
Current assets	$ 246	$ 223
Property, plant and equipment, net	2,278	2,427
Other noncurrent assets	122	112
Total assets	2,646	2,762
Current liabilities	1,349	233
Mortgages and other long-term debt payable	486	1,687
Other noncurrent liabilities	48	42
Total liabilities	$ 1,883	$ 1,962