Fair Value Measurement - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Financial assets, fair value	$ 0thrm_FinancialAssetsFairValueDisclosure	$ 0thrm_FinancialAssetsFairValueDisclosure
Financial liabilities, fair value	0	0
Changes to fair value of assets, realized	$ 0us-gaap_AssetsFairValueAdjustment	$ 0us-gaap_AssetsFairValueAdjustment

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

No definition available.

Name:	us-gaap_FinancialLiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant