Basis of Presentation (Tables)

3 Months Ended

Mar. 31, 2014

Accounting Policies [Abstract]

Summary of Stock Options Outstanding

The following table provides information about our stock options outstanding for the three months ended March 31, 2014 and 2013:

	March 31, 2014					March 31, 2013
				Weighted-					Weighted-
				Average					Average
	Shares			Exercise Price		Shares			Exercise Price
Stock Options:
Outstanding at beginning of period		712,578		$	47.42		335,730		$	42.14
Granted		43,686			71.47		122,357			47.50
Exercised		(20,366	)		33.80		(22,283	)		31.36
Outstanding at end of period		735,898			49.23		435,804			44.19
Exercisable at end of period		137,005		$	47.08		197,943		$	44.52
Weighted-average fair value  of awards granted	$	17.35				$	10.32

Schedule of Vesting Information Stock Options Outstanding

The following table provides vesting information about our stock options outstanding for the three months ended March 31, 2014 and 2013:

	March 31, 2014					March 31, 2013
				Weighted-					Weighted-
				Average					Average
	Shares			Exercise Price		Shares			Exercise Price
Stock Options:
Unvested at beginning of period		609,029		$	47.66		157,298		$	38.57
Granted		43,686			71.47		122,357			47.50
Vested		(53,822	)		44.11		(41,794	)		34.30
Unvested at end of period		598,893		$	49.72		237,861		$	43.92