Incentive Plans (Details) - shares shares in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Incentive Plans [Abstract]
Number of stock options outstanding (in shares)	0	0	0
Number of stock options granted (in shares)	0	0	0
Common stock reserved for issuance [Line Items]
Total common shares reserved for issuance (in shares)	4,430
1993 Stock Incentive Plan [Member]
Common stock reserved for issuance [Line Items]
Total common shares reserved for issuance (in shares)	4,320
Other Employee Benefit Plan [Member]
Common stock reserved for issuance [Line Items]
Total common shares reserved for issuance (in shares)	110