Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2014 Aircraft	Jun. 30, 2014 Aircraft	Dec. 31, 2013 Aircraft
Long-term Purchase Commitment [Line Items]
Total aircraft deposits		$ 13.2
Aggregate estimated probable liability environmental matters		0.2
Aggregate commitments under operating leases		275.0
Operational lease payable		24.8
Lease commitment for aircraft		258.5
Facility lease commitments		16.5
Heavy Helicopters [Member]
Long-term Purchase Commitment [Line Items]
Number of aircrafts acquire under contract			6
Number of aircrafts delivered under contract	1	1
Option to purchase additional number of aircraft		6
Aircraft purchased		6
2014 [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase price for aircraft		71.5
2016 [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase price for aircraft		67.8
2017 [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase price for aircraft		55.7
2018 [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase price for aircraft		127.0
2019 [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase price for aircraft		$ 64.3