Stock Based Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under the plan	563,666
Omnibus Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash-based award paid to a single participant in any calendar year	$ 2,000
Aggregate number of common stock for issuance under the plan	750,000
Period of years for which the 750,000 shares can be granted over	5 years
Shares granted to any single participant in any calendar year	50,000
Stock Options | Omnibus Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term Period	10
Restricted Stock | Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Unrecognized compensation expense, net	6,138
Unrecognized compensation expense, net, weighted average period	1 year 9 months 18 days
Weighted average grant date fair value		$ 104.07	$ 68.80
Total fair value of restricted stock vested	4,696	2,712	2,141
Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercised	2,425
Weighted-average exercise price of options exercised	$ 22.35
Options outstanding	0
Total intrinsic value of options exercised	118	346	250
Phantom Share Units (PSUs) | Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Units granted	10,105
Units vested	3,429
Units forfeited	1,304
Total fair value of units outstanding	$ 421