Stockholders' Equity and Equity Instruments - Activity (Details) - $ / shares	3 Months Ended	9 Months Ended
	Mar. 31, 2015	Sep. 30, 2015
Weighted-average fair value
Reissued shares of treasury stock (in shares)		31,141
TSR PSUs [Member]
Weighted-average fair value
Weighted-average fair value, Granted (in dollars per share)		$ 111.07
Stock Options [Member]
Number
Outstanding at beginning of period (in shares)	278,429	278,429
Granted (in shares)		120,956
Exercised (in shares)		(31,104)
Cancelled/Expired (in shares)		(9,060)
Outstanding at end of period (in shares)		359,221
Weighted-average exercise price
Weighted-average exercise price at beginning of period (in dollars per share)	$ 79.23	$ 79.23
Weighted-average exercise price, Granted (in dollars per share)		91.76
Weighted-average exercise price, Exercised (in dollars per share)		72.20
Weighted-average exercise price, Cancelled/Expired (in dollars per share)		84.81
Weighted-average exercise price at end of period (in dollars per share)		$ 83.88
Weighted-average fair value
Reissued shares of treasury stock (in shares)		31,104
RSUs [Member]
Number
Outstanding at beginning of period (in shares)	88,532	88,532
Granted (in shares)		19,492
Released from restriction (in shares)		(15,952)
Cancelled/Expired (in shares)		(2,188)
Outstanding at end of period (in shares)		89,884
Weighted-average fair value
Weighted-average fair value at beginning of period (in dollars per share)	$ 76.58	$ 76.58
Weighted-average fair value, Granted (in dollars per share)		91.76
Weighted-average fair value, Released from restriction (in dollars per share)		71.69
Weighted-average fair value, Cancelled/Expired (in dollars per share)		81.56
Weighted-average fair value at end of period (in dollars per share)		$ 80.62
Reissued shares of treasury stock (in shares)		15,952
PSUs [Member]
Number
Outstanding at beginning of period (in shares)	59,627	59,627
Granted (in shares)		35,584
Released from restriction (in shares)		(10,454)
Cancelled/Expired (in shares)		(6,689)
Outstanding at end of period (in shares)		78,068
Weighted-average fair value
Weighted-average fair value at beginning of period (in dollars per share)	$ 88.69	$ 88.69
Weighted-average fair value, Granted (in dollars per share)		100.49
Weighted-average fair value, Released from restriction (in dollars per share)		74.49
Weighted-average fair value, Cancelled/Expired (in dollars per share)		81.47
Weighted-average fair value at end of period (in dollars per share)		$ 96.59
Attainment level of PSU at grant date		100.00%
PSU at grant date (in shares per unit)		1
PSUs [Member] | Grant Date 2012 [Member]
Number
Cancelled/Expired (in shares)	(4,443)
Weighted-average fair value
Reissued shares of treasury stock (in shares)	10,454	10,454