Pension Benefit and Other Postretirement Benefit Plans - Summary of Changes in Fair Value of Guaranteed Deposit Account's Level 3 Assets (Details) (Pension Benefits [Member], Guaranteed deposit account [Member], Fair Value, Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified	4 Months Ended
	Apr. 30, 2013
Pension Benefits [Member] | Guaranteed deposit account [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 15,402
Realized gains (losses)	0
Unrealized gains relating to instruments still held at the reporting date	1,177
Purchases, sales, issuances and settlements (net)	13
Transfers in and/or out of Level 3	0
Ending Balance	$ 16,592