XML 91 R79.htm IDEA: XBRL DOCUMENT v3.7.0.1
Commitments and Contingencies (Narratives) (Details)
$ in Millions
 3 Months Ended 63 Months Ended
Mar. 31, 2017
USD ($)
claim
Mar. 31, 2017
USD ($)
claim
Dec. 31, 2016
USD ($)
petition
Dec. 31, 2015
petition
Dec. 31, 2014
petition
Dec. 31, 2013
petition
Dec. 31, 2012
petition
Loss contingency              
Accrued liability for the outcomes of non-income based tax audits | $ $ 1.5 $ 1.5 $ 1.5        
Indemnification liability | $ 1.7 1.7 $ 1.7        
Litigation and Claims              
Ad valorem tax benefit | $ 4.2 64.9          
Ad valorem tax benefit agreed to by a number of appraisal review boards and county appraisal districts | $ 13.7 13.7          
Ad valorem tax benefit in litigation | $ $ 51.2 $ 51.2          
Number of petitions | petition     113 120 115 109 176
Number of cases appealed | claim 3 3          
Loss Contingencies [Line Items]              
Number of pending cases | claim 5 5          
Number of settled cases | claim 3            
Same Judge              
Loss Contingencies [Line Items]              
Number of settled cases | claim 2            
United ISD              
Loss Contingencies [Line Items]              
Number of pending cases | claim 4 4