Employee Benefit Plans Fair Value (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	$ 44		$ 318
Available-for-sale Securities	18,040		18,183
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	752	[1]	751	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	721	[1]	736	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | S&P 500 Index [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	8,234	[1]	7,321	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	6	[1]	98	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	6	[1]	98	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	7	[1]	110	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	1,495	[1]	1,595	[1]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	72	[1]	85
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Passive Bond Market [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	1,992	[2]	1,880	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	4,435	[2]	4,390	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	1	[2]	107	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5	[2]	55	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	6	[2]	79	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5	[2]	55	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	240	[2]	261	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	3	[2]	57	[2]
Other Postretirement Benefit Plan [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	16	[2]	187	[2]
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	0		0
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | S&P 500 Index [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Passive Bond Market [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	44		318
Available-for-sale Securities	18,040		18,183
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	752	[1]	751
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	721	[1]	736
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | S&P 500 Index [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	8,234	[1]	7,321
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	6	[1]	98
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	6	[1]	98
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	7	[1]	110
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	1,495	[1]	1,595
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	72	[1]	85
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Passive Bond Market [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	1,992	[2]	1,880
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	4,435	[2]	4,390
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	1	[2]	107
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5	[2]	55
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	6	[2]	79
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5	[2]	55
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	240	[2]	261
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	3	[2]	57
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	16	[2]	187
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	0		0
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | S&P 500 Index [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Passive Bond Market [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Other Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Defined Contribution Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	8,700		7,800		7,200
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	126		168
Available-for-sale Securities	556,051		516,352
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	16,605	[1]	13,764	[1]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	15,264	[1]	13,664	[1]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	48,560	[1]	42,094	[1]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	48,785	[1]	42,102	[1]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	54,775	[1]	47,227	[1]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	22,634	[1]	20,015	[1]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	7,650	[1]	6,250
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	23,177	[2]	82,639	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	12,269	[2]	44,762	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	41,451	[2]	24,401	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	52,767	[2]	32,700	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	41,475	[2]	24,122	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5,692	[2]	5,876	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	24,504	[2]	25,150	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	133,160	[2]	83,147	[2]
Defined Contribution Pension [Member] | Estimate of Fair Value Measurement [Member] | Debt Securities [Member] | Participating Group Annuity Contract [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	7,157	[2]	8,271	[2]
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	0		0
Available-for-sale Securities	0		0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] | Participating Group Annuity Contract [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	126		168
Available-for-sale Securities	556,051		516,352
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	16,605	[1]	13,764
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	15,264	[1]	13,664
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	48,560	[1]	42,094
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	48,785	[1]	42,102
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	54,775	[1]	47,227
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	22,634	[1]	20,015
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	7,650	[1]	6,250
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	23,177	[2]	82,639
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	12,269	[2]	44,762
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	41,451	[2]	24,401
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	52,767		32,700
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	41,475		24,122
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5,692		5,876
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	24,504	[2]	25,150
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	133,160	[2]	83,147
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] | Participating Group Annuity Contract [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	7,157	[2]	8,271
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash and cash equivalents	0		0
Available-for-sale Securities	0		0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Small Midcap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Small Midcap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Large Cap Growth [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Large Cap Value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | US Large Cap Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Non US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[1]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | US Core [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Long Duration [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Long Duration Investment Grade [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Long Duration Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Opportunistic [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Non US Passive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0		0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Active Long Corporate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	0	[2]	0
Defined Contribution Pension [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Participating Group Annuity Contract [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	$ 0	[2]	$ 0

[1] This category consists of active and passive managed equity funds, which are invested in multiple strategies to diversify risks and reduce volatility.

[2] This category consists of investment grade bonds of issuers from diverse industries, debt securities issued by international, national, state and local governments, and asset-backed securities. This includes both active and passive managed funds.