Stockholders' Equity and Noncontrolling Interests - Stock-Based Compensation Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Shares			54,930
Exercised, Shares			(116)
Expired, Shares			(16,646)
Ending balance, Shares	38,168		38,168
Weighted-Average Grant Date Fair Value, Beginning balance			$ 114.86
Weighted-Average Grant Date Fair Value, Exercised			73.97
Weighted-Average Grant Date Fair Value, Expired			114.57
Weighted-Average Grant Date Fair Value, Ending balance	$ 115.11		$ 115.11
Weighted-average contractual remaining life (in years)			1 year 5 months 9 days
Exercisable shares	38,154		38,154
Weighted-average exercise price			$ 115.11
Weighted-average exercise price exercisable shares	$ 115.12		$ 115.12
Compensation expense (credit)	$ (14,000)	$ (19,000)	$ (82,000)	$ (33,000)
Fair value of liability award	$ 27,000		$ 27,000		$ 167,000
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Shares			142,667
Exercised, Shares			(66,667)
Ending balance, Shares	76,000		76,000
Weighted-Average Grant Date Fair Value, Beginning balance			$ 107.39
Weighted-Average Grant Date Fair Value, Exercised			103.58
Weighted-Average Grant Date Fair Value, Ending balance	$ 110.73		$ 110.73
Weighted-average contractual remaining life (in years)			3 years 8 months 16 days
Weighted-average exercise price			$ 110.73
Compensation expense (credit)	$ 282,000	496,000	$ 935,000	2,577,000
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Shares			128,214
Granted, Shares			83,093
Exercised, Shares			(72,093)
Forfeited, Shares			(281)
Ending balance, Shares	138,933		138,933
Weighted-Average Grant Date Fair Value, Beginning balance			$ 95.82
Weighted-Average Grant Date Fair Value, Granted			104.75
Weighted-Average Grant Date Fair Value, Exercised			90.85
Weighted-Average Grant Date Fair Value, Forfeited			105.02
Weighted-Average Grant Date Fair Value, Ending balance	$ 103.73		$ 103.73
Weighted-average contractual remaining life (in years)			1 year 11 months 12 days
Weighted-average exercise price			$ 103.73
Compensation expense (credit)	$ 1,114,000	$ 522,000	$ 5,421,000	$ 6,447,000
Fair value of liability award	$ 19,134,000		$ 19,134,000		$ 16,301,000