Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock option exercised	0	0	0
Shares available for future issuance	1,500,000
Number of Shares
Number of shares, beginning balance	99,775
Number of shares, forfeited or expired	0
Number of shares, ending balance	99,775.000	99,775
Weighted Average Exercise Price
Weighted average exercise price, beginning balance (in dollars per share)	$ 54.15
Weighted average exercise price, forfeited or expired (in dollars per share)	$ 0.00
Weighted average exercise price, ending balance (in dollars per share)	$ 54.15	$ 54.15
Additional Disclosures
Number of shares, vested or expected to vest	99,775
Number of shares, exercisable	99,775
Weighted average exercise price, vested or expected to vest (in dollars per share)	$ 54.15
Weighted average exercise price, exercisable (in dollars per share)	$ 54.15
Weighted average remaining contractual life (years)	1 year 10 months 24 days	2 years 10 months 24 days
Weighted average remaining contractual life (years), vested or expected to vest	1 year 10 months 24 days
Weighted average remaining contractual life (years), exercisable	1 year 10 months 24 days
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, granted (in dollars per share)	$ 21.59	$ 20.49	$ 16.30
Number of Units
Number of units, vested (less than)	100,000
Fair values of vested restricted stock and stock options	$ 0	$ 500,000	$ 1,500,000