Commitments and Contingencies Schedule of Contributions made to Multiemployer Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Multiemployer Plans [Line Items]
Contributions	$ 10,818		$ 4,752		$ 2,941
Pension Plans [Member]
Multiemployer Plans [Line Items]
Contributions	2,871	[1]	1,201	[1]	768	[1]
Pension Plans [Member] | Multiemployer Plan, Individually Insignificant Multiemployer Plans [Member]
Multiemployer Plans [Line Items]
Contributions	800		400		300
Health Plans [Member]
Multiemployer Plans [Line Items]
Contributions	7,628	[2]	3,319	[2]	2,013	[2]
Health Plans [Member] | Multiemployer Plan, Individually Insignificant Multiemployer Plans [Member]
Multiemployer Plans [Line Items]
Contributions	1,500		800		500
Other [Member]
Multiemployer Plans [Line Items]
Contributions	319	[3]	232	[3]	160	[3]
Other [Member] | Multiemployer Plan, Individually Insignificant Multiemployer Plans [Member]
Multiemployer Plans [Line Items]
Contributions	$ 80		$ 50		$ 80

[1] Pension plans include $0.8 million, $0.4 million and $0.3 million for the years ended 2014, 2013 and 2012, respectively, from multiemployer plans not discussed above.

[2] Health plans include $1.5 million, $0.8 million and $0.5 million for the years ended 2014, 2013 and 2012, respectively, from multiemployer plans not discussed above.

[3] ther includes $0.08 million, $0.05 million and $0.08 million for the years ended 2014, 2013 and 2012, respectively, in connection with other multiemployer plans not discussed above for union costs which were not itemized between pension and health plans.