Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net pension plan gain (loss), tax provision (benefit)	$ 386		$ 386
Net pension plan curtailment and settlement expense, tax provision	193		193
Amortization of deferred pension plan, tax provision	253	732	758	2,192
Noble-Cayman [Member]
Net pension plan gain (loss), tax provision (benefit)	386		386
Net pension plan curtailment and settlement expense, tax provision	193		193
Amortization of deferred pension plan, tax provision	$ 253	$ 732	$ 758	$ 2,192