Employee Benefits (Narrative) (Details) (USD $)	12 Months Ended			120 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Annual measurement impact on project benefit obligation	$ 14,000,000
Impact of discount rate	9,200,000
Impact of adopting new mortality tables	3,800,000
Curtailment		(4,400,000)
Defined contribution plan, employer matching contribution, percent of employee gross pay	4.00%
Defined contribution plan, employer matching contributions	1,800,000	1,600,000	1,400,000
Other incentive-based compensation expense	13,800,000	13,400,000	13,500,000
Deferred compensation plan, accrued liability	7,700,000	7,100,000
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment	0	(4,061,000)
Accumulated benefit obligation	64,000,000	53,100,000
Estimated amortization of prior service cost (credit) from accumulated other comprehensive loss into net period benefit cost, next year	(23,000)
Estimated amortization of (gain) loss from accumulated other comprehensive loss into net period benefit cost, next year		1,200,000
Fair value of equity securities, maximum percentage held by a single issuer	10.00%
Estimated future employer contributions in next fiscal year	3,000,000
Qualified Pension Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, minimum	50.00%
Target plan asset allocation, investment ranges, maximum	70.00%
Qualified Pension Plan [Member] | Small-Cap Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, maximum	20.00%
Qualified Pension Plan [Member] | Mid-Cap Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, maximum	20.00%
Qualified Pension Plan [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, maximum	30.00%
Qualified Pension Plan [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, minimum	30.00%
Target plan asset allocation, investment ranges, maximum	50.00%
Qualified Pension Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, minimum	0.00%
Target plan asset allocation, investment ranges, maximum	10.00%
Qualified Pension Plan [Member] | High Yield Bond [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, investment ranges, maximum	10.00%
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Available-for-sale securities and other short-term investments, rabbi trusts	10,400,000	7,500,000
Curtailment	0	(360,000)
Accumulated benefit obligation	12,100,000	10,400,000
Estimated amortization of prior service cost (credit) from accumulated other comprehensive loss into net period benefit cost, next year	(1,000)
Estimated amortization of (gain) loss from accumulated other comprehensive loss into net period benefit cost, next year		244,000
Estimated future employer contributions in next fiscal year	$ 791,000
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Transition Period Pension Plan Amendment				10 years