Fair Value Measurements (Fair Value Assets(Liabilities) Measured On Recurring Basis) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonqualified savings plan assets	$ 13,083	$ 12,838	$ 14,339
Investment in equity securities	116,261	131,584
Total	129,344	144,422	14,339
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonqualified savings plan assets	12,571	12,259	14,339
Investment in equity securities	0	0
Total	12,571	12,259	14,339
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonqualified savings plan assets	512	579	0
Investment in equity securities	116,261	131,584
Total	116,773	132,163	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonqualified savings plan assets	0	0	0
Investment in equity securities	0	0
Total	$ 0	$ 0	$ 0